diff --git a/src/ol/render/webgl/circlereplay/index.js b/src/ol/render/webgl/circlereplay/index.js
index 5ab2677c5d..e947dc1505 100644
--- a/src/ol/render/webgl/circlereplay/index.js
+++ b/src/ol/render/webgl/circlereplay/index.js
@@ -164,7 +164,7 @@ ol.render.webgl.CircleReplay.prototype.finish = function(context) {
  */
 ol.render.webgl.CircleReplay.prototype.getDeleteResourcesFunction = function(context) {
   // We only delete our stuff here. The shaders and the program may
-  // be used by other PolygonReplay instances (for other layers). And
+  // be used by other CircleReplay instances (for other layers). And
   // they will be deleted when disposing of the ol.webgl.Context
   // object.
   ol.DEBUG && console.assert(this.verticesBuffer,
diff --git a/src/ol/render/webgl/index.js b/src/ol/render/webgl/index.js
index 564bdad94a..8dc0eb2973 100644
--- a/src/ol/render/webgl/index.js
+++ b/src/ol/render/webgl/index.js
@@ -61,7 +61,7 @@ ol.render.webgl.lineStringInstruction = {
 };
 
 /**
- * Calcualtes the orientation of a triangle based on the determinant method.
+ * Calculates the orientation of a triangle based on the determinant method.
  * @param {number} x1 First X coordinate.
  * @param {number} y1 First Y coordinate.
  * @param {number} x2 Second X coordinate.
diff --git a/src/ol/render/webgl/linestringreplay/index.js b/src/ol/render/webgl/linestringreplay/index.js
index 911ca33955..a54280be12 100644
--- a/src/ol/render/webgl/linestringreplay/index.js
+++ b/src/ol/render/webgl/linestringreplay/index.js
@@ -150,6 +150,7 @@ ol.render.webgl.LineStringReplay.prototype.drawCoordinates_ = function(flatCoord
         break;
       } else {
         //For the compiler not to complain. This will never be [0, 0].
+        ol.DEBUG && console.assert(p0, 'p0 should be defined');
         p0 = p0 || [0, 0];
 
         numVertices = this.addVertices_(p0, p1, [0, 0],
@@ -189,6 +190,7 @@ ol.render.webgl.LineStringReplay.prototype.drawCoordinates_ = function(flatCoord
       p2 = [flatCoordinates[i + stride], flatCoordinates[i + stride + 1]];
     }
 
+    // We group CW and straight lines, thus the not so inituitive CCW checking function.
     sign = ol.render.webgl.triangleIsCounterClockwise(p0[0], p0[1], p1[0], p1[1], p2[0], p2[1])
         ? -1 : 1;
 
@@ -232,6 +234,7 @@ ol.render.webgl.LineStringReplay.prototype.drawCoordinates_ = function(flatCoord
   if (closed) {
     //Link the last triangle/rhombus to the first one.
     //n will never be numVertices / 7 here. However, the compiler complains otherwise.
+    ol.DEBUG && console.assert(n, 'n should be defined');
     n = n || numVertices / 7;
     sign = ol.geom.flat.orient.linearRingIsClockwise([p0[0], p0[1], p1[0], p1[1], p2[0], p2[1]], 0, 6, 2)
         ? 1 : -1;
diff --git a/src/ol/render/webgl/polygonreplay/index.js b/src/ol/render/webgl/polygonreplay/index.js
index 937d87ed9a..79d8042b7b 100644
--- a/src/ol/render/webgl/polygonreplay/index.js
+++ b/src/ol/render/webgl/polygonreplay/index.js
@@ -297,6 +297,7 @@ ol.render.webgl.PolygonReplay.prototype.triangulate_ = function(list, rtree) {
           // introduce touching segments. However, the original data may have some.
           if (!this.resolveLocalSelfIntersections_(list, rtree, true)) {
             // Something went wrong.
+            ol.DEBUG && console.assert(false, 'Unexpected simple polygon geometry');
             break;
           }
         }
diff --git a/src/ol/structs/linkedlist.js b/src/ol/structs/linkedlist.js
index 7b51fde9fe..19fe515550 100644
--- a/src/ol/structs/linkedlist.js
+++ b/src/ol/structs/linkedlist.js
@@ -4,6 +4,7 @@ goog.provide('ol.structs.LinkedList');
  * Creates an empty linked list structure.
  *
  * @constructor
+ * @struct
  * @param {boolean=} opt_circular The last item is connected to the first one,
  * and the first item to the last one. Default is true.
  */