diff --git a/doc/errors/index.md b/doc/errors/index.md
index c31432c265..2f52e265fd 100644
--- a/doc/errors/index.md
+++ b/doc/errors/index.md
@@ -220,3 +220,7 @@ Unknown `tierSizeCalculation` configured.
 ### 54
 
 Hex color should have 3 or 6 digits.
+
+### 55
+
+The `{-y}` placeholder requires a tile grid with extent.
diff --git a/src/ol/format/esrijsonformat.js b/src/ol/format/esrijsonformat.js
index 45452c21ff..bafe6e858a 100644
--- a/src/ol/format/esrijsonformat.js
+++ b/src/ol/format/esrijsonformat.js
@@ -80,8 +80,6 @@ ol.format.EsriJSON.readGeometry_ = function(object, opt_options) {
     }
   }
   var geometryReader = ol.format.EsriJSON.GEOMETRY_READERS_[type];
-  goog.DEBUG && console.assert(geometryReader,
-      'geometryReader should be defined');
   return /** @type {ol.geom.Geometry} */ (
       ol.format.Feature.transformWithOptions(
           geometryReader(object), false, opt_options));
@@ -217,7 +215,6 @@ ol.format.EsriJSON.getGeometryLayout_ = function(object) {
  * @return {ol.geom.Geometry} MultiPoint.
  */
 ol.format.EsriJSON.readMultiPointGeometry_ = function(object) {
-  goog.DEBUG && console.assert(object.points, 'object.points should be defined');
   var layout = ol.format.EsriJSON.getGeometryLayout_(object);
   return new ol.geom.MultiPoint(object.points, layout);
 };
@@ -229,7 +226,6 @@ ol.format.EsriJSON.readMultiPointGeometry_ = function(object) {
  * @return {ol.geom.Geometry} MultiPolygon.
  */
 ol.format.EsriJSON.readMultiPolygonGeometry_ = function(object) {
-  goog.DEBUG && console.assert(object.rings);
   goog.DEBUG && console.assert(object.rings.length > 1,
       'object.rings should have length larger than 1');
   var layout = ol.format.EsriJSON.getGeometryLayout_(object);
@@ -575,7 +571,6 @@ ol.format.EsriJSON.prototype.readProjectionFromObject = function(object) {
  */
 ol.format.EsriJSON.writeGeometry_ = function(geometry, opt_options) {
   var geometryWriter = ol.format.EsriJSON.GEOMETRY_WRITERS_[geometry.getType()];
-  goog.DEBUG && console.assert(geometryWriter, 'geometryWriter should be defined');
   return geometryWriter(/** @type {ol.geom.Geometry} */ (
       ol.format.Feature.transformWithOptions(geometry, true, opt_options)),
       opt_options);
diff --git a/src/ol/format/geojsonformat.js b/src/ol/format/geojsonformat.js
index 906e58e2c3..eee8a870e4 100644
--- a/src/ol/format/geojsonformat.js
+++ b/src/ol/format/geojsonformat.js
@@ -70,7 +70,6 @@ ol.format.GeoJSON.readGeometry_ = function(object, opt_options) {
     return null;
   }
   var geometryReader = ol.format.GeoJSON.GEOMETRY_READERS_[object.type];
-  goog.DEBUG && console.assert(geometryReader, 'geometryReader should be defined');
   return /** @type {ol.geom.Geometry} */ (
       ol.format.Feature.transformWithOptions(
           geometryReader(object), false, opt_options));
@@ -179,7 +178,6 @@ ol.format.GeoJSON.readPolygonGeometry_ = function(object) {
  */
 ol.format.GeoJSON.writeGeometry_ = function(geometry, opt_options) {
   var geometryWriter = ol.format.GeoJSON.GEOMETRY_WRITERS_[geometry.getType()];
-  goog.DEBUG && console.assert(geometryWriter, 'geometryWriter should be defined');
   return geometryWriter(/** @type {ol.geom.Geometry} */ (
       ol.format.Feature.transformWithOptions(geometry, true, opt_options)),
       opt_options);
diff --git a/src/ol/format/topojsonformat.js b/src/ol/format/topojsonformat.js
index 8673fd28e2..5a8d8955c5 100644
--- a/src/ol/format/topojsonformat.js
+++ b/src/ol/format/topojsonformat.js
@@ -249,7 +249,6 @@ ol.format.TopoJSON.readFeatureFromGeometry_ = function(object, arcs,
   var geometry;
   var type = object.type;
   var geometryReader = ol.format.TopoJSON.GEOMETRY_READERS_[type];
-  goog.DEBUG && console.assert(geometryReader, 'geometryReader should be defined');
   if ((type === 'Point') || (type === 'MultiPoint')) {
     geometry = geometryReader(object, scale, translate);
   } else {
diff --git a/src/ol/geom/circle.js b/src/ol/geom/circle.js
index 1ccf620bea..70ba62aa86 100644
--- a/src/ol/geom/circle.js
+++ b/src/ol/geom/circle.js
@@ -222,8 +222,6 @@ ol.geom.Circle.prototype.setFlatCoordinates = function(layout, flatCoordinates)
  * @api
  */
 ol.geom.Circle.prototype.setRadius = function(radius) {
-  goog.DEBUG && console.assert(this.flatCoordinates,
-      'truthy this.flatCoordinates expected');
   this.flatCoordinates[this.stride] = this.flatCoordinates[0] + radius;
   this.changed();
 };
diff --git a/src/ol/geom/flat/flipflatgeom.js b/src/ol/geom/flat/flipflatgeom.js
index 4391f22bcc..cfbbe89c93 100644
--- a/src/ol/geom/flat/flipflatgeom.js
+++ b/src/ol/geom/flat/flipflatgeom.js
@@ -16,8 +16,6 @@ ol.geom.flat.flip.flipXY = function(flatCoordinates, offset, end, stride, opt_de
     dest = opt_dest;
     destOffset = opt_destOffset !== undefined ? opt_destOffset : 0;
   } else {
-    goog.DEBUG && console.assert(opt_destOffset === undefined,
-        'opt_destOffSet should be defined');
     dest = [];
     destOffset = 0;
   }
diff --git a/src/ol/graticule.js b/src/ol/graticule.js
index dc174f5631..543046af84 100644
--- a/src/ol/graticule.js
+++ b/src/ol/graticule.js
@@ -455,8 +455,6 @@ ol.Graticule.prototype.handlePostCompose_ = function(e) {
  * @private
  */
 ol.Graticule.prototype.updateProjectionInfo_ = function(projection) {
-  goog.DEBUG && console.assert(projection, 'projection cannot be null');
-
   var epsg4326Projection = ol.proj.get('EPSG:4326');
 
   var extent = projection.getExtent();
@@ -474,7 +472,6 @@ ol.Graticule.prototype.updateProjectionInfo_ = function(projection) {
   var minLatP = worldExtentP[1];
   var minLonP = worldExtentP[0];
 
-  goog.DEBUG && console.assert(extent, 'extent cannot be null');
   goog.DEBUG && console.assert(maxLat !== undefined, 'maxLat should be defined');
   goog.DEBUG && console.assert(maxLon !== undefined, 'maxLon should be defined');
   goog.DEBUG && console.assert(minLat !== undefined, 'minLat should be defined');
diff --git a/src/ol/image.js b/src/ol/image.js
index 396960f451..081157b450 100644
--- a/src/ol/image.js
+++ b/src/ol/image.js
@@ -157,8 +157,6 @@ ol.Image.prototype.setImage = function(image) {
  * @private
  */
 ol.Image.prototype.unlistenImage_ = function() {
-  goog.DEBUG && console.assert(this.imageListenerKeys_,
-      'this.imageListenerKeys_ should not be null');
   this.imageListenerKeys_.forEach(ol.events.unlistenByKey);
   this.imageListenerKeys_ = null;
 };
diff --git a/src/ol/imagetile.js b/src/ol/imagetile.js
index ddb84fe3e6..104651d644 100644
--- a/src/ol/imagetile.js
+++ b/src/ol/imagetile.js
@@ -164,8 +164,6 @@ ol.ImageTile.prototype.load = function() {
  * @private
  */
 ol.ImageTile.prototype.unlistenImage_ = function() {
-  goog.DEBUG && console.assert(this.imageListenerKeys_,
-      'this.imageListenerKeys_ should not be null');
   this.imageListenerKeys_.forEach(ol.events.unlistenByKey);
   this.imageListenerKeys_ = null;
 };
diff --git a/src/ol/interaction/doubleclickzoominteraction.js b/src/ol/interaction/doubleclickzoominteraction.js
index bb47f5b448..24bb329773 100644
--- a/src/ol/interaction/doubleclickzoominteraction.js
+++ b/src/ol/interaction/doubleclickzoominteraction.js
@@ -54,7 +54,6 @@ ol.interaction.DoubleClickZoom.handleEvent = function(mapBrowserEvent) {
     var anchor = mapBrowserEvent.coordinate;
     var delta = browserEvent.shiftKey ? -this.delta_ : this.delta_;
     var view = map.getView();
-    goog.DEBUG && console.assert(view, 'map must have a view');
     ol.interaction.Interaction.zoomByDelta(
         map, view, delta, anchor, this.duration_);
     mapBrowserEvent.preventDefault();
diff --git a/src/ol/interaction/draganddropinteraction.js b/src/ol/interaction/draganddropinteraction.js
index def3cfefd1..00226c8e4a 100644
--- a/src/ol/interaction/draganddropinteraction.js
+++ b/src/ol/interaction/draganddropinteraction.js
@@ -96,11 +96,9 @@ ol.interaction.DragAndDrop.handleStop_ = function(event) {
 ol.interaction.DragAndDrop.prototype.handleResult_ = function(file, event) {
   var result = event.target.result;
   var map = this.getMap();
-  goog.DEBUG && console.assert(map, 'map must be set');
   var projection = this.projection_;
   if (!projection) {
     var view = map.getView();
-    goog.DEBUG && console.assert(view, 'map must have view');
     projection = view.getProjection();
     goog.DEBUG && console.assert(projection !== undefined,
         'projection should be defined');
diff --git a/src/ol/interaction/drawinteraction.js b/src/ol/interaction/drawinteraction.js
index 95a2097303..25c46e3f93 100644
--- a/src/ol/interaction/drawinteraction.js
+++ b/src/ol/interaction/drawinteraction.js
@@ -644,7 +644,6 @@ ol.interaction.Draw.prototype.removeLastPoint = function() {
  */
 ol.interaction.Draw.prototype.finishDrawing = function() {
   var sketchFeature = this.abortDrawing_();
-  goog.DEBUG && console.assert(sketchFeature, 'sketchFeature expected to be truthy');
   var coordinates = this.sketchCoords_;
   var geometry = /** @type {ol.geom.SimpleGeometry} */ (sketchFeature.getGeometry());
   if (this.mode_ === ol.interaction.DrawMode.LINE_STRING) {
@@ -712,7 +711,6 @@ ol.interaction.Draw.prototype.extend = function(feature) {
   var geometry = feature.getGeometry();
   goog.DEBUG && console.assert(this.mode_ == ol.interaction.DrawMode.LINE_STRING,
       'interaction mode must be "line"');
-  goog.DEBUG && console.assert(geometry, 'feature must have a geometry');
   goog.DEBUG && console.assert(geometry.getType() == ol.geom.GeometryType.LINE_STRING,
       'feature geometry must be a line string');
   var lineString = /** @type {ol.geom.LineString} */ (geometry);
diff --git a/src/ol/interaction/keyboardpaninteraction.js b/src/ol/interaction/keyboardpaninteraction.js
index 48aea0a30c..55541c85a4 100644
--- a/src/ol/interaction/keyboardpaninteraction.js
+++ b/src/ol/interaction/keyboardpaninteraction.js
@@ -87,7 +87,6 @@ ol.interaction.KeyboardPan.handleEvent = function(mapBrowserEvent) {
         keyCode == ol.events.KeyCode.UP)) {
       var map = mapBrowserEvent.map;
       var view = map.getView();
-      goog.DEBUG && console.assert(view, 'map must have view');
       var mapUnitsDelta = view.getResolution() * this.pixelDelta_;
       var deltaX = 0, deltaY = 0;
       if (keyCode == ol.events.KeyCode.DOWN) {
diff --git a/src/ol/interaction/keyboardzoominteraction.js b/src/ol/interaction/keyboardzoominteraction.js
index a543d6947b..747474e9dd 100644
--- a/src/ol/interaction/keyboardzoominteraction.js
+++ b/src/ol/interaction/keyboardzoominteraction.js
@@ -74,7 +74,6 @@ ol.interaction.KeyboardZoom.handleEvent = function(mapBrowserEvent) {
       var delta = (charCode == '+'.charCodeAt(0)) ? this.delta_ : -this.delta_;
       map.render();
       var view = map.getView();
-      goog.DEBUG && console.assert(view, 'map must have view');
       ol.interaction.Interaction.zoomByDelta(
           map, view, delta, undefined, this.duration_);
       mapBrowserEvent.preventDefault();
diff --git a/src/ol/interaction/modifyinteraction.js b/src/ol/interaction/modifyinteraction.js
index 7ed29c5aa7..542bcf2634 100644
--- a/src/ol/interaction/modifyinteraction.js
+++ b/src/ol/interaction/modifyinteraction.js
@@ -841,7 +841,6 @@ ol.interaction.Modify.prototype.insertVertex_ = function(segmentData, vertex) {
 
   this.setGeometryCoordinates_(geometry, coordinates);
   var rTree = this.rBush_;
-  goog.DEBUG && console.assert(segment !== undefined, 'segment should be defined');
   rTree.remove(segmentData);
   this.updateSegmentIndices_(geometry, index, depth, 1);
   var newSegmentData = /** @type {ol.ModifySegmentDataType} */ ({
diff --git a/src/ol/interaction/mousewheelzoominteraction.js b/src/ol/interaction/mousewheelzoominteraction.js
index f125a8fa13..0f010cf8a8 100644
--- a/src/ol/interaction/mousewheelzoominteraction.js
+++ b/src/ol/interaction/mousewheelzoominteraction.js
@@ -131,7 +131,6 @@ ol.interaction.MouseWheelZoom.prototype.doZoom_ = function(map) {
   var delta = ol.math.clamp(this.delta_, -maxDelta, maxDelta);
 
   var view = map.getView();
-  goog.DEBUG && console.assert(view, 'map must have view');
 
   map.render();
   ol.interaction.Interaction.zoomByDelta(map, view, -delta, this.lastAnchor_,
diff --git a/src/ol/map.js b/src/ol/map.js
index 776bf98ad1..754aebd5ba 100644
--- a/src/ol/map.js
+++ b/src/ol/map.js
@@ -478,9 +478,7 @@ ol.inherits(ol.Map, ol.Object);
  * @api stable
  */
 ol.Map.prototype.addControl = function(control) {
-  var controls = this.getControls();
-  goog.DEBUG && console.assert(controls !== undefined, 'controls should be defined');
-  controls.push(control);
+  this.getControls().push(control);
 };
 
 
@@ -490,10 +488,7 @@ ol.Map.prototype.addControl = function(control) {
  * @api stable
  */
 ol.Map.prototype.addInteraction = function(interaction) {
-  var interactions = this.getInteractions();
-  goog.DEBUG && console.assert(interactions !== undefined,
-      'interactions should be defined');
-  interactions.push(interaction);
+  this.getInteractions().push(interaction);
 };
 
 
@@ -516,9 +511,7 @@ ol.Map.prototype.addLayer = function(layer) {
  * @api stable
  */
 ol.Map.prototype.addOverlay = function(overlay) {
-  var overlays = this.getOverlays();
-  goog.DEBUG && console.assert(overlays !== undefined, 'overlays should be defined');
-  overlays.push(overlay);
+  this.getOverlays().push(overlay);
 };
 
 
@@ -973,10 +966,7 @@ ol.Map.prototype.handleMapBrowserEvent = function(mapBrowserEvent) {
   }
   this.focus_ = mapBrowserEvent.coordinate;
   mapBrowserEvent.frameState = this.frameState_;
-  var interactions = this.getInteractions();
-  goog.DEBUG && console.assert(interactions !== undefined,
-      'interactions should be defined');
-  var interactionsArray = interactions.getArray();
+  var interactionsArray = this.getInteractions().getArray();
   var i;
   if (this.dispatchEvent(mapBrowserEvent) !== false) {
     for (i = interactionsArray.length - 1; i >= 0; i--) {
@@ -1199,9 +1189,7 @@ ol.Map.prototype.render = function() {
  * @api stable
  */
 ol.Map.prototype.removeControl = function(control) {
-  var controls = this.getControls();
-  goog.DEBUG && console.assert(controls !== undefined, 'controls should be defined');
-  return controls.remove(control);
+  return this.getControls().remove(control);
 };
 
 
@@ -1213,10 +1201,7 @@ ol.Map.prototype.removeControl = function(control) {
  * @api stable
  */
 ol.Map.prototype.removeInteraction = function(interaction) {
-  var interactions = this.getInteractions();
-  goog.DEBUG && console.assert(interactions !== undefined,
-      'interactions should be defined');
-  return interactions.remove(interaction);
+  return this.getInteractions().remove(interaction);
 };
 
 
@@ -1241,9 +1226,7 @@ ol.Map.prototype.removeLayer = function(layer) {
  * @api stable
  */
 ol.Map.prototype.removeOverlay = function(overlay) {
-  var overlays = this.getOverlays();
-  goog.DEBUG && console.assert(overlays !== undefined, 'overlays should be defined');
-  return overlays.remove(overlay);
+  return this.getOverlays().remove(overlay);
 };
 
 
diff --git a/src/ol/overlay.js b/src/ol/overlay.js
index 9ad9ef38b2..82f93f2048 100644
--- a/src/ol/overlay.js
+++ b/src/ol/overlay.js
@@ -430,9 +430,6 @@ ol.Overlay.prototype.panIntoView_ = function() {
  * @private
  */
 ol.Overlay.prototype.getRect_ = function(element, size) {
-  goog.DEBUG && console.assert(element, 'element should be defined');
-  goog.DEBUG && console.assert(size !== undefined, 'size should be defined');
-
   var box = element.getBoundingClientRect();
   var offsetX = box.left + ol.global.pageXOffset;
   var offsetY = box.top + ol.global.pageYOffset;
@@ -494,11 +491,8 @@ ol.Overlay.prototype.updatePixelPosition = function() {
  * @protected
  */
 ol.Overlay.prototype.updateRenderedPosition = function(pixel, mapSize) {
-  goog.DEBUG && console.assert(pixel, 'pixel should not be null');
-  goog.DEBUG && console.assert(mapSize !== undefined, 'mapSize should be defined');
   var style = this.element_.style;
   var offset = this.getOffset();
-  goog.DEBUG && console.assert(Array.isArray(offset), 'offset should be an array');
 
   var positioning = this.getPositioning();
   goog.DEBUG && console.assert(positioning !== undefined,
diff --git a/src/ol/render/box.js b/src/ol/render/box.js
index ff5dabd2f6..592e9621d7 100644
--- a/src/ol/render/box.js
+++ b/src/ol/render/box.js
@@ -63,8 +63,6 @@ ol.render.Box.prototype.disposeInternal = function() {
 ol.render.Box.prototype.render_ = function() {
   var startPixel = this.startPixel_;
   var endPixel = this.endPixel_;
-  goog.DEBUG && console.assert(startPixel, 'this.startPixel_ must be truthy');
-  goog.DEBUG && console.assert(endPixel, 'this.endPixel_ must be truthy');
   var px = 'px';
   var style = this.element_.style;
   style.left = Math.min(startPixel[0], endPixel[0]) + px;
@@ -106,11 +104,6 @@ ol.render.Box.prototype.setPixels = function(startPixel, endPixel) {
  * Creates or updates the cached geometry.
  */
 ol.render.Box.prototype.createOrUpdateGeometry = function() {
-  goog.DEBUG && console.assert(this.startPixel_,
-      'this.startPixel_ must be truthy');
-  goog.DEBUG && console.assert(this.endPixel_,
-      'this.endPixel_ must be truthy');
-  goog.DEBUG && console.assert(this.map_, 'this.map_ must be truthy');
   var startPixel = this.startPixel_;
   var endPixel = this.endPixel_;
   var pixels = [
diff --git a/src/ol/render/canvas/canvasimmediate.js b/src/ol/render/canvas/canvasimmediate.js
index 514b889f5e..22b7bc4f2c 100644
--- a/src/ol/render/canvas/canvasimmediate.js
+++ b/src/ol/render/canvas/canvasimmediate.js
@@ -498,7 +498,6 @@ ol.render.canvas.Immediate.prototype.drawFeature = function(feature, style) {
     return;
   }
   this.setStyle(style);
-  goog.DEBUG && console.assert(geometry, 'geometry must be truthy');
   this.drawGeometry(geometry);
 };
 
@@ -852,10 +851,7 @@ ol.render.canvas.Immediate.prototype.setImageStyle = function(imageStyle) {
     var imageImage = imageStyle.getImage(1);
     var imageOrigin = imageStyle.getOrigin();
     var imageSize = imageStyle.getSize();
-    goog.DEBUG && console.assert(imageAnchor, 'imageAnchor must be truthy');
     goog.DEBUG && console.assert(imageImage, 'imageImage must be truthy');
-    goog.DEBUG && console.assert(imageOrigin, 'imageOrigin must be truthy');
-    goog.DEBUG && console.assert(imageSize, 'imageSize must be truthy');
     this.imageAnchorX_ = imageAnchor[0];
     this.imageAnchorY_ = imageAnchor[1];
     this.imageHeight_ = imageSize[1];
diff --git a/src/ol/render/vector.js b/src/ol/render/vector.js
index d5d0160c61..a7c1b16d44 100644
--- a/src/ol/render/vector.js
+++ b/src/ol/render/vector.js
@@ -116,8 +116,6 @@ ol.renderer.vector.renderFeature_ = function(
   var simplifiedGeometry = geometry.getSimplifiedGeometry(squaredTolerance);
   var geometryRenderer =
       ol.renderer.vector.GEOMETRY_RENDERERS_[simplifiedGeometry.getType()];
-  goog.DEBUG && console.assert(geometryRenderer !== undefined,
-      'geometryRenderer should be defined');
   geometryRenderer(replayGroup, simplifiedGeometry, style, feature);
 };
 
@@ -135,8 +133,6 @@ ol.renderer.vector.renderGeometryCollectionGeometry_ = function(replayGroup, geo
   for (i = 0, ii = geometries.length; i < ii; ++i) {
     var geometryRenderer =
         ol.renderer.vector.GEOMETRY_RENDERERS_[geometries[i].getType()];
-    goog.DEBUG && console.assert(geometryRenderer !== undefined,
-        'geometryRenderer should be defined');
     geometryRenderer(replayGroup, geometries[i], style, feature);
   }
 };
diff --git a/src/ol/render/webgl/webglreplay.js b/src/ol/render/webgl/webglreplay.js
index cbff43e21f..2f817d3770 100644
--- a/src/ol/render/webgl/webglreplay.js
+++ b/src/ol/render/webgl/webglreplay.js
@@ -987,9 +987,6 @@ ol.render.webgl.ReplayGroup.prototype.getReplay = function(zIndex, replayType) {
   var replay = this.replays_[replayType];
   if (replay === undefined) {
     var constructor = ol.render.webgl.BATCH_CONSTRUCTORS_[replayType];
-    goog.DEBUG && console.assert(constructor !== undefined,
-        replayType +
-        ' constructor missing from ol.render.webgl.BATCH_CONSTRUCTORS_');
     replay = new constructor(this.tolerance_, this.maxExtent_);
     this.replays_[replayType] = replay;
   }
diff --git a/src/ol/renderer/canvas/canvastilelayerrenderer.js b/src/ol/renderer/canvas/canvastilelayerrenderer.js
index d364f50403..932275acc0 100644
--- a/src/ol/renderer/canvas/canvastilelayerrenderer.js
+++ b/src/ol/renderer/canvas/canvastilelayerrenderer.js
@@ -142,7 +142,6 @@ ol.renderer.canvas.TileLayer.prototype.prepareFrame = function(
       if (!drawableTile(tile) && tile.interimTile) {
         tile = tile.interimTile;
       }
-      goog.DEBUG && console.assert(tile);
       if (drawableTile(tile)) {
         tilesToDrawByZ[z][tile.tileCoord.toString()] = tile;
         continue;
diff --git a/src/ol/renderer/canvas/canvasvectorlayerrenderer.js b/src/ol/renderer/canvas/canvasvectorlayerrenderer.js
index 7134a8c025..8bc0057c7f 100644
--- a/src/ol/renderer/canvas/canvasvectorlayerrenderer.js
+++ b/src/ol/renderer/canvas/canvasvectorlayerrenderer.js
@@ -172,7 +172,6 @@ ol.renderer.canvas.VectorLayer.prototype.forEachFeatureAtCoordinate = function(c
          * @return {?} Callback result.
          */
         function(feature) {
-          goog.DEBUG && console.assert(feature !== undefined, 'received a feature');
           var key = ol.getUid(feature).toString();
           if (!(key in features)) {
             features[key] = true;
diff --git a/src/ol/renderer/canvas/canvasvectortilelayerrenderer.js b/src/ol/renderer/canvas/canvasvectortilelayerrenderer.js
index e5897c16fd..0106ec561f 100644
--- a/src/ol/renderer/canvas/canvasvectortilelayerrenderer.js
+++ b/src/ol/renderer/canvas/canvasvectortilelayerrenderer.js
@@ -306,7 +306,6 @@ ol.renderer.canvas.VectorTileLayer.prototype.forEachFeatureAtCoordinate = functi
          * @return {?} Callback result.
          */
         function(feature) {
-          goog.DEBUG && console.assert(feature, 'received a feature');
           var key = ol.getUid(feature).toString();
           if (!(key in features)) {
             features[key] = true;
diff --git a/src/ol/renderer/dom/domtilelayerrenderer.js b/src/ol/renderer/dom/domtilelayerrenderer.js
index b5cf1015a4..d297d2afad 100644
--- a/src/ol/renderer/dom/domtilelayerrenderer.js
+++ b/src/ol/renderer/dom/domtilelayerrenderer.js
@@ -128,7 +128,6 @@ ol.renderer.dom.TileLayer.prototype.prepareFrame = function(frameState, layerSta
       if (!drawable && tile.interimTile) {
         tile = tile.interimTile;
       }
-      goog.DEBUG && console.assert(tile);
       tileState = tile.getState();
       if (tileState == ol.TileState.LOADED) {
         tilesToDrawByZ[z][tile.tileCoord.toString()] = tile;
diff --git a/src/ol/renderer/dom/domvectorlayerrenderer.js b/src/ol/renderer/dom/domvectorlayerrenderer.js
index f4355fed4b..ae70e64efb 100644
--- a/src/ol/renderer/dom/domvectorlayerrenderer.js
+++ b/src/ol/renderer/dom/domvectorlayerrenderer.js
@@ -190,7 +190,6 @@ ol.renderer.dom.VectorLayer.prototype.forEachFeatureAtCoordinate = function(coor
          * @return {?} Callback result.
          */
         function(feature) {
-          goog.DEBUG && console.assert(feature !== undefined, 'received a feature');
           var key = ol.getUid(feature).toString();
           if (!(key in features)) {
             features[key] = true;
diff --git a/src/ol/renderer/maprenderer.js b/src/ol/renderer/maprenderer.js
index dab4024c33..922952f79c 100644
--- a/src/ol/renderer/maprenderer.js
+++ b/src/ol/renderer/maprenderer.js
@@ -135,7 +135,6 @@ ol.renderer.Map.prototype.forEachFeatureAtCoordinate = function(coordinate, fram
    * @return {?} Callback result.
    */
   function forEachFeatureAtCoordinate(feature, layer) {
-    goog.DEBUG && console.assert(feature !== undefined, 'received a feature');
     var key = ol.getUid(feature).toString();
     var managed = frameState.layerStates[ol.getUid(layer)].managed;
     if (!(key in frameState.skippedFeatureUids && !managed)) {
diff --git a/src/ol/renderer/webgl/webglmaprenderer.js b/src/ol/renderer/webgl/webglmaprenderer.js
index 3bc83b689d..71f338824b 100644
--- a/src/ol/renderer/webgl/webglmaprenderer.js
+++ b/src/ol/renderer/webgl/webglmaprenderer.js
@@ -182,8 +182,6 @@ ol.renderer.webgl.Map.prototype.bindTileTexture = function(tile, tileSize, tileG
   var tileKey = tile.getKey();
   if (this.textureCache_.containsKey(tileKey)) {
     var textureCacheEntry = this.textureCache_.get(tileKey);
-    goog.DEBUG && console.assert(textureCacheEntry,
-        'a texture cache entry exists for key %s', tileKey);
     gl.bindTexture(ol.webgl.TEXTURE_2D, textureCacheEntry.texture);
     if (textureCacheEntry.magFilter != magFilter) {
       gl.texParameteri(
diff --git a/src/ol/renderer/webgl/webgltilelayerrenderer.js b/src/ol/renderer/webgl/webgltilelayerrenderer.js
index 65e5aedb13..5674335a78 100644
--- a/src/ol/renderer/webgl/webgltilelayerrenderer.js
+++ b/src/ol/renderer/webgl/webgltilelayerrenderer.js
@@ -258,7 +258,6 @@ ol.renderer.webgl.TileLayer.prototype.prepareFrame = function(frameState, layerS
         if (!drawable && tile.interimTile) {
           tile = tile.interimTile;
         }
-        goog.DEBUG && console.assert(tile);
         tileState = tile.getState();
         if (tileState == ol.TileState.LOADED) {
           if (mapRenderer.isTileTextureLoaded(tile)) {
diff --git a/src/ol/renderer/webgl/webglvectorlayerrenderer.js b/src/ol/renderer/webgl/webglvectorlayerrenderer.js
index af11ceca83..9c6f5dc0db 100644
--- a/src/ol/renderer/webgl/webglvectorlayerrenderer.js
+++ b/src/ol/renderer/webgl/webglvectorlayerrenderer.js
@@ -120,7 +120,6 @@ ol.renderer.webgl.VectorLayer.prototype.forEachFeatureAtCoordinate = function(co
          * @return {?} Callback result.
          */
         function(feature) {
-          goog.DEBUG && console.assert(feature !== undefined, 'received a feature');
           var key = ol.getUid(feature).toString();
           if (!(key in features)) {
             features[key] = true;
diff --git a/src/ol/reproj/tile.js b/src/ol/reproj/tile.js
index 7a99b971b1..670c08dc34 100644
--- a/src/ol/reproj/tile.js
+++ b/src/ol/reproj/tile.js
@@ -332,8 +332,6 @@ ol.reproj.Tile.prototype.load = function() {
  * @private
  */
 ol.reproj.Tile.prototype.unlistenSources_ = function() {
-  goog.DEBUG && console.assert(this.sourcesListenerKeys_,
-      'this.sourcesListenerKeys_ should not be null');
   this.sourcesListenerKeys_.forEach(ol.events.unlistenByKey);
   this.sourcesListenerKeys_ = null;
 };
diff --git a/src/ol/source/imagevectorsource.js b/src/ol/source/imagevectorsource.js
index 00568958f8..e8f82a33a5 100644
--- a/src/ol/source/imagevectorsource.js
+++ b/src/ol/source/imagevectorsource.js
@@ -168,7 +168,6 @@ ol.source.ImageVector.prototype.forEachFeatureAtCoordinate = function(
          * @return {?} Callback result.
          */
         function(feature) {
-          goog.DEBUG && console.assert(feature !== undefined, 'passed a feature');
           var key = ol.getUid(feature).toString();
           if (!(key in features)) {
             features[key] = true;
diff --git a/src/ol/source/tilesource.js b/src/ol/source/tilesource.js
index eb2d81e210..49e502b3bd 100644
--- a/src/ol/source/tilesource.js
+++ b/src/ol/source/tilesource.js
@@ -282,7 +282,6 @@ ol.source.Tile.prototype.getTileCoordForTileUrlFunction = function(tileCoord, op
   var projection = opt_projection !== undefined ?
       opt_projection : this.getProjection();
   var tileGrid = this.getTileGridForProjection(projection);
-  goog.DEBUG && console.assert(tileGrid, 'tile grid needed');
   if (this.getWrapX() && projection.isGlobal()) {
     tileCoord = ol.tilecoord.wrapX(tileCoord, tileGrid, projection);
   }
diff --git a/src/ol/style/iconstyle.js b/src/ol/style/iconstyle.js
index b16385087c..df6fffa8c5 100644
--- a/src/ol/style/iconstyle.js
+++ b/src/ol/style/iconstyle.js
@@ -604,9 +604,6 @@ ol.style.IconImage_.prototype.replaceColor_ = function() {
     return;
   }
 
-  goog.DEBUG && console.assert(this.canvas_ !== null,
-      'this.canvas_ must not be null');
-
   this.canvas_.width = this.image_.width;
   this.canvas_.height = this.image_.height;
 
@@ -634,8 +631,6 @@ ol.style.IconImage_.prototype.replaceColor_ = function() {
  * @private
  */
 ol.style.IconImage_.prototype.unlistenImage_ = function() {
-  goog.DEBUG && console.assert(this.imageListenerKeys_,
-      'we must have listeners registered');
   this.imageListenerKeys_.forEach(ol.events.unlistenByKey);
   this.imageListenerKeys_ = null;
 };
diff --git a/src/ol/style/style.js b/src/ol/style/style.js
index 45b6cdfbed..91aec95aa1 100644
--- a/src/ol/style/style.js
+++ b/src/ol/style/style.js
@@ -335,6 +335,5 @@ ol.style.createDefaultEditingStyles = function() {
  * @return {ol.geom.Geometry|ol.render.Feature|undefined} Geometry to render.
  */
 ol.style.defaultGeometryFunction = function(feature) {
-  goog.DEBUG && console.assert(feature, 'feature must not be null');
   return feature.getGeometry();
 };
diff --git a/src/ol/tilegrid/tilegrid.js b/src/ol/tilegrid/tilegrid.js
index c5c528b8ec..facc390a07 100644
--- a/src/ol/tilegrid/tilegrid.js
+++ b/src/ol/tilegrid/tilegrid.js
@@ -228,8 +228,6 @@ ol.tilegrid.TileGrid.prototype.getOrigin = function(z) {
   if (this.origin_) {
     return this.origin_;
   } else {
-    goog.DEBUG && console.assert(this.origins_,
-        'origins cannot be null if origin is null');
     goog.DEBUG && console.assert(this.minZoom <= z && z <= this.maxZoom,
         'given z is not in allowed range (%s <= %s <= %s)',
         this.minZoom, z, this.maxZoom);
@@ -458,8 +456,6 @@ ol.tilegrid.TileGrid.prototype.getTileSize = function(z) {
   if (this.tileSize_) {
     return this.tileSize_;
   } else {
-    goog.DEBUG && console.assert(this.tileSizes_,
-        'tileSizes cannot be null if tileSize is null');
     goog.DEBUG && console.assert(this.minZoom <= z && z <= this.maxZoom,
         'z is not in allowed range (%s <= %s <= %s',
         this.minZoom, z, this.maxZoom);
diff --git a/src/ol/tileurlfunction.js b/src/ol/tileurlfunction.js
index e27ef0e78e..f03c4fef19 100644
--- a/src/ol/tileurlfunction.js
+++ b/src/ol/tileurlfunction.js
@@ -34,8 +34,7 @@ ol.TileUrlFunction.createFromTemplate = function(template, tileGrid) {
               .replace(dashYRegEx, function() {
                 var z = tileCoord[0];
                 var range = tileGrid.getFullTileRange(z);
-                goog.DEBUG && console.assert(range,
-                    'The {-y} template requires a tile grid with extent');
+                ol.assert(range, 55); // The {-y} placeholder requires a tile grid with extent
                 var y = range.getHeight() + tileCoord[2];
                 return y.toString();
               });