getFeatureAtPixel always returns array

changelog/upgrade-notes.md

@@ -279,6 +279,10 @@ The `getGetFeatureInfoUrl` of `ol/source/ImageWMS` and `ol/source/TileWMS` is no
 
 The `SelectInteraction` is removed. There are two examples ([Select Features by Hover](https://openlayers.org/en/master/examples/select-hover-features.html) and [Select multiple Features](https://openlayers.org/en/master/examples/select-multiple-features.html) which show how similar results can be achieved by using more basic methods.
 
+##### `getFeatureAtPixel` returns always an array
+
+`getFeatureAtPixel` returns now an empty array instead of `null` if no features were found. 
+
 #### Other changes
 
 ##### Allow declutter in image render mode