I'm updating my fleet of web map apps to provide a message to the users (general public, non-GIS) if any of the map/feature services fails to load. It will be a simple modal window.
Here's my hang-up: What do I tell the user? Simply state there was an error loading some layers and the map is not displaying all intended layers? Or also provide the user with the bad URL and/or the server error code (400,404, 500, etc.)?
I guess it's really a question of what is the most appropriate error message to provide the user. I'm using Esri Leaflet, but this is a concept that is valid for any type of web map app development, at least in my opinion.