diff --git a/src/ol/control/ZoomToExtent.js b/src/ol/control/ZoomToExtent.js
index d883244cd6..76933eaddd 100644
--- a/src/ol/control/ZoomToExtent.js
+++ b/src/ol/control/ZoomToExtent.js
@@ -38,7 +38,7 @@ class ZoomToExtent extends Control {
     });
 
     /**
-     * @type {?import("../extent.js").Extent}
+     * @type {?import("../extent.js").Extent|null}
      * @protected
      */
     this.extent = options.extent ? options.extent : null;
diff --git a/src/ol/dom.js b/src/ol/dom.js
index 8134220939..84f68d9fe9 100644
--- a/src/ol/dom.js
+++ b/src/ol/dom.js
@@ -83,7 +83,7 @@ export function replaceNode(newNode, oldNode) {
 
 /**
  * @param {Node} node The node to remove.
- * @return {Node} The node that was removed or null.
+ * @return {Node|null} The node that was removed or null.
  */
 export function removeNode(node) {
   return node && node.parentNode ? node.parentNode.removeChild(node) : null;
diff --git a/src/ol/format/MVT.js b/src/ol/format/MVT.js
index dbdf15cbf5..1b061c80c5 100644
--- a/src/ol/format/MVT.js
+++ b/src/ol/format/MVT.js
@@ -80,7 +80,7 @@ class MVT extends FeatureFormat {
 
     /**
      * @private
-     * @type {Array<string>}
+     * @type {Array<string>|null}
      */
     this.layers_ = options.layers ? options.layers : null;
 
diff --git a/src/ol/format/WMSGetFeatureInfo.js b/src/ol/format/WMSGetFeatureInfo.js
index b1e2f97658..65e4a54f01 100644
--- a/src/ol/format/WMSGetFeatureInfo.js
+++ b/src/ol/format/WMSGetFeatureInfo.js
@@ -54,20 +54,20 @@ class WMSGetFeatureInfo extends XMLFeature {
 
     /**
      * @private
-     * @type {Array<string>}
+     * @type {Array<string>|null}
      */
     this.layers_ = options.layers ? options.layers : null;
   }
 
   /**
-   * @return {Array<string>} layers
+   * @return {Array<string>|null} layers
    */
   getLayers() {
     return this.layers_;
   }
 
   /**
-   * @param {Array<string>} layers Layers to parse.
+   * @param {Array<string>|null} layers Layers to parse.
    */
   setLayers(layers) {
     this.layers_ = layers;
diff --git a/src/ol/interaction/DragAndDrop.js b/src/ol/interaction/DragAndDrop.js
index 2a318c0b64..30e68fe30d 100644
--- a/src/ol/interaction/DragAndDrop.js
+++ b/src/ol/interaction/DragAndDrop.js
@@ -168,7 +168,7 @@ class DragAndDrop extends Interaction {
 
     /**
      * @private
-     * @type {HTMLElement}
+     * @type {HTMLElement|null}
      */
     this.target = options.target ? options.target : null;
   }
diff --git a/src/ol/interaction/Draw.js b/src/ol/interaction/Draw.js
index 64c7be6c98..21054f8b82 100644
--- a/src/ol/interaction/Draw.js
+++ b/src/ol/interaction/Draw.js
@@ -257,14 +257,14 @@ class Draw extends PointerInteraction {
 
     /**
      * Target source for drawn features.
-     * @type {VectorSource}
+     * @type {VectorSource|null}
      * @private
      */
     this.source_ = options.source ? options.source : null;
 
     /**
      * Target collection for drawn features.
-     * @type {import("../Collection.js").default<Feature>}
+     * @type {import("../Collection.js").default<Feature>|null}
      * @private
      */
     this.features_ = options.features ? options.features : null;
@@ -1022,7 +1022,7 @@ class Draw extends PointerInteraction {
 
   /**
    * Stop drawing without adding the sketch feature to the target layer.
-   * @return {Feature<import("../geom/SimpleGeometry.js").default>} The sketch feature (or null if none).
+   * @return {Feature<import("../geom/SimpleGeometry.js").default>|null} The sketch feature (or null if none).
    * @private
    */
   abortDrawing_() {
diff --git a/src/ol/interaction/Snap.js b/src/ol/interaction/Snap.js
index 91d4da84b9..613a3aac80 100644
--- a/src/ol/interaction/Snap.js
+++ b/src/ol/interaction/Snap.js
@@ -115,7 +115,7 @@ class Snap extends PointerInteraction {
     super(pointerOptions);
 
     /**
-     * @type {import("../source/Vector.js").default}
+     * @type {import("../source/Vector.js").default|null}
      * @private
      */
     this.source_ = options.source ? options.source : null;
@@ -133,7 +133,7 @@ class Snap extends PointerInteraction {
     this.edge_ = options.edge !== undefined ? options.edge : true;
 
     /**
-     * @type {import("../Collection.js").default<import("../Feature.js").default>}
+     * @type {import("../Collection.js").default<import("../Feature.js").default>|null}
      * @private
      */
     this.features_ = options.features ? options.features : null;
diff --git a/src/ol/interaction/Translate.js b/src/ol/interaction/Translate.js
index b5d54cd61e..8d0d9326f3 100644
--- a/src/ol/interaction/Translate.js
+++ b/src/ol/interaction/Translate.js
@@ -169,7 +169,7 @@ class Translate extends PointerInteraction {
     this.startCoordinate_ = null;
 
     /**
-     * @type {Collection<import("../Feature.js").default>}
+     * @type {Collection<import("../Feature.js").default>|null}
      * @private
      */
     this.features_ = options.features !== undefined ? options.features : null;
diff --git a/src/ol/layer/Base.js b/src/ol/layer/Base.js
index 6141cd84d0..b99f5dd28d 100644
--- a/src/ol/layer/Base.js
+++ b/src/ol/layer/Base.js
@@ -119,7 +119,7 @@ class BaseLayer extends BaseObject {
      * @private
      */
     this.className_ =
-      properties.className !== undefined ? options.className : 'ol-layer';
+      properties.className !== undefined ? properties.className : 'ol-layer';
     delete properties.className;
 
     this.setProperties(properties);
@@ -288,7 +288,7 @@ class BaseLayer extends BaseObject {
   }
 
   /**
-   * Sets the backgrlound color.
+   * Sets the background color.
    * @param {BackgroundColor} [opt_background] Background color.
    */
   setBackground(opt_background) {
diff --git a/src/ol/source/Image.js b/src/ol/source/Image.js
index 914f0ab77b..7253aca49d 100644
--- a/src/ol/source/Image.js
+++ b/src/ol/source/Image.js
@@ -127,7 +127,7 @@ class ImageSource extends Source {
 
     /**
      * @private
-     * @type {Array<number>}
+     * @type {Array<number>|null}
      */
     this.resolutions_ =
       options.resolutions !== undefined ? options.resolutions : null;
@@ -146,7 +146,7 @@ class ImageSource extends Source {
   }
 
   /**
-   * @return {Array<number>} Resolutions.
+   * @return {Array<number>|null} Resolutions.
    */
   getResolutions() {
     return this.resolutions_;
diff --git a/src/ol/source/ImageStatic.js b/src/ol/source/ImageStatic.js
index 95c30c808f..de7ae14f1e 100644
--- a/src/ol/source/ImageStatic.js
+++ b/src/ol/source/ImageStatic.js
@@ -87,7 +87,7 @@ class Static extends ImageSource {
 
     /**
      * @private
-     * @type {import("../size.js").Size}
+     * @type {import("../size.js").Size|null}
      */
     this.imageSize_ = options.imageSize ? options.imageSize : null;
 
diff --git a/src/ol/source/Source.js b/src/ol/source/Source.js
index 1642417d74..1e41d81f0e 100644
--- a/src/ol/source/Source.js
+++ b/src/ol/source/Source.js
@@ -150,7 +150,7 @@ class Source extends BaseObject {
 
   /**
    * @abstract
-   * @return {Array<number>|undefined} Resolutions.
+   * @return {Array<number>|null} Resolutions.
    */
   getResolutions() {
     return abstract();
diff --git a/src/ol/source/Tile.js b/src/ol/source/Tile.js
index d172824399..b09e812d4c 100644
--- a/src/ol/source/Tile.js
+++ b/src/ol/source/Tile.js
@@ -93,14 +93,13 @@ class TileSource extends Source {
       options.tilePixelRatio !== undefined ? options.tilePixelRatio : 1;
 
     /**
-     * @type {import("../tilegrid/TileGrid.js").default}
+     * @type {import("../tilegrid/TileGrid.js").default|null}
      */
     this.tileGrid = options.tileGrid !== undefined ? options.tileGrid : null;
 
     const tileSize = [256, 256];
-    const tileGrid = options.tileGrid;
-    if (tileGrid) {
-      toSize(tileGrid.getTileSize(tileGrid.getMinZoom()), tileSize);
+    if (this.tileGrid) {
+      toSize(this.tileGrid.getTileSize(this.tileGrid.getMinZoom()), tileSize);
     }
 
     /**
@@ -233,9 +232,12 @@ class TileSource extends Source {
   }
 
   /**
-   * @return {Array<number>} Resolutions.
+   * @return {Array<number>|null} Resolutions.
    */
   getResolutions() {
+    if (!this.tileGrid) {
+      return null;
+    }
     return this.tileGrid.getResolutions();
   }
 
@@ -254,7 +256,7 @@ class TileSource extends Source {
 
   /**
    * Return the tile grid of the tile source.
-   * @return {import("../tilegrid/TileGrid.js").default} Tile grid.
+   * @return {import("../tilegrid/TileGrid.js").default|null} Tile grid.
    * @api
    */
   getTileGrid() {
diff --git a/src/ol/source/Vector.js b/src/ol/source/Vector.js
index 77f4f61bd8..e9ff757885 100644
--- a/src/ol/source/Vector.js
+++ b/src/ol/source/Vector.js
@@ -827,7 +827,7 @@ class VectorSource extends Source {
    * `source.getFeatureById(2)` will return a feature with id `'2'` or `2`.
    *
    * @param {string|number} id Feature identifier.
-   * @return {import("../Feature.js").default<Geometry>} The feature (or `null` if not found).
+   * @return {import("../Feature.js").default<Geometry>|null} The feature (or `null` if not found).
    * @api
    */
   getFeatureById(id) {
@@ -839,7 +839,7 @@ class VectorSource extends Source {
    * Get a feature by its internal unique identifier (using `getUid`).
    *
    * @param {string} uid Feature identifier.
-   * @return {import("../Feature.js").default<Geometry>} The feature (or `null` if not found).
+   * @return {import("../Feature.js").default<Geometry>|null} The feature (or `null` if not found).
    */
   getFeatureByUid(uid) {
     const feature = this.uidIndex_[uid];
diff --git a/src/ol/source/VectorTile.js b/src/ol/source/VectorTile.js
index 4351345dd9..61036abdea 100644
--- a/src/ol/source/VectorTile.js
+++ b/src/ol/source/VectorTile.js
@@ -142,7 +142,7 @@ class VectorTile extends UrlTile {
 
     /**
      * @private
-     * @type {import("../format/Feature.js").default}
+     * @type {import("../format/Feature.js").default|null}
      */
     this.format_ = options.format ? options.format : null;
 
diff --git a/src/ol/style/Fill.js b/src/ol/style/Fill.js
index cb96102514..092cb237bc 100644
--- a/src/ol/style/Fill.js
+++ b/src/ol/style/Fill.js
@@ -4,7 +4,7 @@
 
 /**
  * @typedef {Object} Options
- * @property {import("../color.js").Color|import("../colorlike.js").ColorLike} [color=null] A color, gradient or pattern.
+ * @property {import("../color.js").Color|import("../colorlike.js").ColorLike|null} [color=null] A color, gradient or pattern.
  * See {@link module:ol/color~Color} and {@link module:ol/colorlike~ColorLike} for possible formats.
  * Default null; if null, the Canvas/renderer default black will be used.
  */
@@ -23,7 +23,7 @@ class Fill {
 
     /**
      * @private
-     * @type {import("../color.js").Color|import("../colorlike.js").ColorLike}
+     * @type {import("../color.js").Color|import("../colorlike.js").ColorLike|null}
      */
     this.color_ = options.color !== undefined ? options.color : null;
   }
@@ -42,7 +42,7 @@ class Fill {
 
   /**
    * Get the fill color.
-   * @return {import("../color.js").Color|import("../colorlike.js").ColorLike} Color.
+   * @return {import("../color.js").Color|import("../colorlike.js").ColorLike|null} Color.
    * @api
    */
   getColor() {
@@ -52,7 +52,7 @@ class Fill {
   /**
    * Set the color.
    *
-   * @param {import("../color.js").Color|import("../colorlike.js").ColorLike} color Color.
+   * @param {import("../color.js").Color|import("../colorlike.js").ColorLike|null} color Color.
    * @api
    */
   setColor(color) {
diff --git a/src/ol/style/Style.js b/src/ol/style/Style.js
index 4e2bb3bf7d..516a4b3bbf 100644
--- a/src/ol/style/Style.js
+++ b/src/ol/style/Style.js
@@ -455,7 +455,7 @@ export function toFunction(obj) {
 }
 
 /**
- * @type {Array<Style>}
+ * @type {Array<Style>|null}
  */
 let defaultStyles = null;
 
diff --git a/src/ol/style/Text.js b/src/ol/style/Text.js
index 5a129772ac..2c044ed8c0 100644
--- a/src/ol/style/Text.js
+++ b/src/ol/style/Text.js
@@ -168,7 +168,7 @@ class Text {
 
     /**
      * @private
-     * @type {Array<number>}
+     * @type {Array<number>|null}
      */
     this.padding_ = options.padding === undefined ? null : options.padding;
   }
@@ -201,7 +201,7 @@ class Text {
       backgroundStroke: this.getBackgroundStroke()
         ? this.getBackgroundStroke().clone()
         : undefined,
-      padding: this.getPadding(),
+      padding: this.getPadding() || undefined,
     });
   }
 
@@ -359,7 +359,7 @@ class Text {
 
   /**
    * Get the padding for the text.
-   * @return {Array<number>} Padding.
+   * @return {Array<number>|null} Padding.
    * @api
    */
   getPadding() {
@@ -530,7 +530,7 @@ class Text {
   /**
    * Set the padding (`[top, right, bottom, left]`).
    *
-   * @param {!Array<number>} padding Padding.
+   * @param {Array<number>|null} padding Padding.
    * @api
    */
   setPadding(padding) {
diff --git a/src/ol/tilegrid/TileGrid.js b/src/ol/tilegrid/TileGrid.js
index 019b67a5fe..13c6fe94ec 100644
--- a/src/ol/tilegrid/TileGrid.js
+++ b/src/ol/tilegrid/TileGrid.js
@@ -117,7 +117,7 @@ class TileGrid {
 
     /**
      * @private
-     * @type {import("../coordinate.js").Coordinate}
+     * @type {import("../coordinate.js").Coordinate|null}
      */
     this.origin_ = options.origin !== undefined ? options.origin : null;
 
diff --git a/src/ol/worker/webgl.js b/src/ol/worker/webgl.js
index 3d2f1269c1..b4c5a9a6b5 100644
--- a/src/ol/worker/webgl.js
+++ b/src/ol/worker/webgl.js
@@ -29,7 +29,7 @@ worker.onmessage = (event) => {
     const indexBuffer = new Uint32Array(indicesCount);
     const vertexBuffer = new Float32Array(verticesCount);
 
-    let bufferPositions = null;
+    let bufferPositions;
     for (let i = 0; i < renderInstructions.length; i += instructionsCount) {
       bufferPositions = writePointFeatureToBuffers(
         renderInstructions,