configuring the Pop-up in the Local Layer Widget can I check if the image (or other files) URL exists?
if an Image does not exist I want to show another image....is it possible?
No that type of custom logic is not available in the LL popup. You would have to add some code to the map manger or something like evaluate the maps.infoWindow on selection-change event to see if it is the layer you want to work with and then check the field and do your logic.
Retrieving data ...