forEachFeatureAtPixel shouldn't fail if layer has no source

src/ol/renderer/maprenderer.js

@@ -170,9 +170,11 @@ ol.renderer.Map.prototype.forEachFeatureAtCoordinate =
         (ol.layer.Layer.visibleAtResolution(layerState, viewResolution) &&
         layerFilter.call(thisArg2, layer))) {
       var layerRenderer = this.getLayerRenderer(layer);
-      result = layerRenderer.forEachFeatureAtCoordinate(
+      if (!goog.isNull(layer.getSource())) {
-          layer.getSource().getWrapX() ? translatedCoordinate : coordinate,
+        result = layerRenderer.forEachFeatureAtCoordinate(
-          frameState, callback, thisArg);
+            layer.getSource().getWrapX() ? translatedCoordinate : coordinate,
+            frameState, callback, thisArg);
+      }
       if (result) {
         return result;
       }

test/spec/ol/renderer/canvas/canvasmaprenderer.test.js

@@ -58,12 +58,21 @@ describe('ol.renderer.canvas.Map', function() {
     it('filters managed layers', function() {
       map.addLayer(layer);
       map.renderSync();
-      cb = sinon.spy();
+      var cb = sinon.spy();
       map.forEachFeatureAtPixel(map.getPixelFromCoordinate([0, 0]), cb, null,
           function() { return false; });
       expect(cb).to.not.be.called();
     });
 
+    it('doesn\'t fail with layer with no source', function() {
+      map.addLayer(new ol.layer.Tile());
+      map.renderSync();
+      expect(function() {
+        map.forEachFeatureAtPixel(map.getPixelFromCoordinate([0, 0]),
+            function() {});
+      }).to.not.throwException();
+    });
+
   });
 
   describe('#renderFrame()', function() {
@@ -92,6 +101,7 @@ goog.require('ol.Feature');
 goog.require('ol.Map');
 goog.require('ol.View');
 goog.require('ol.geom.Point');
+goog.require('ol.layer.Tile');
 goog.require('ol.layer.Vector');
 goog.require('ol.renderer.canvas.Layer');
 goog.require('ol.renderer.canvas.Map');