Examples of when PHP calls the function set by set_exception_handler with an Error object? And is it always fatal? Can it be caught? [duplicate]

I’m trying to write a handler for exceptions. I’ve noticed that sometimes it’s passed an Error object. (As opposed to an Exception object). I’d like to know:

1. Some examples of what triggers this to happen
2. Whether when an Error object is passed to the exception handler, is it always fatal?
3. Can the Error object being thrown be caught, stopping it from being fatal? And if it isn’t caught, is it always fatal?

Thanks