Uncaught (in promise) TypeError: l.addFilter is not a function.

## Here are issue details  and how to  reproduce.
[how-to-ensure-ol-ext-modifies-openlayers-layer-prototype-before-usage-after-npm](https://stackoverflow.com/questions/79732997/how-to-ensure-ol-ext-modifies-openlayers-layer-prototype-before-usage-after-npm)