Error Handling?

It already does -- see the Language/Exceptions part of the manual, or Commands/Index/Catch.

Here's the example (not sure if you have Max at this point):

Rem
Catch defines an exception handler following a Try..EndTry Block.
End Rem

Try
	Repeat
		a:+1
		Print a
		If a>20 Throw "chunks"
	Forever
Catch a$
	Print "caught exception "+a$
EndTry