[Genhis] Unexpected error with empty string for local_expression

[Schmendrick]

If a noise expression is an empty string, Factorio loads just fine and then throws "Parameter 'arg_register' expects Number, None given." when you try to actually use the expression live.

However, if a noise expression/function's local_expression is an empty string (and that expression is not unused), Factorio crashes during load with a generic "Error Util.cpp:95: Unexpected error occurred." You can pretty easily infer the problem is in noise compilation by looking at the log file but I would appreciate a more informative error (and, presumably, also a catch for when a main expression is empty during load).

[Bilka]

Moved to bug reports, mods should not be able to cause an "Unexpected error".

[Genhis]

Fixed for 2.0.48.