After doing some cleaning with materials, it would be very nice to be able to automatically check the world for in-existent objects or materials, that cause my game to crash when playing it, but I have no idea where the issue is.

Wouldn't it be possible to have a button that checks this and shows me (like on objects, with a pulsing red texture) where the issue is? Or in the Valve way, when an object can't be loaded don't crash the project because of it, just load a huge red "ERROR" object, so the developer can easily find it and fix it.

It's not something very important, but it would save a lot of time when a design error occurs in world editing.