Fix invalid return address 0 in GDScript

[jordi-star]

Fixes #70936, created by 0c15844.
In the past, all method returns would have a temporary return address assigned to it, even if its return type is null. Now, the return address can be empty (Address:NIL, which has an address of 0), but the bytecode still attempts to send the returned value to this address. Address:NIL is the default state of the Address class when using an empty constructor, so sending the returned value here probably messes some stuff up for things that use Address() to represent an empty address (Such as the unary operator).

I'm not too knowledgable on the inner workings of the VM/Compiler, so this may not be the correct fix. The bug is gone and all tests pass, so I assume this was the problem...
If this is not the correct fix, please let me know 👍

[jordi-star]

cc @vnen

[vnen]

This really only work by accident because the MethodBind call and the ptrcall instructions have the same arguments. It that ceases to be the case in the future this will introduce problems. I also think there are other cases where this is a problem, not only with ptrcall.

In any case, I have a fix for this bug ready: #71107

[akien-mga]

Superseded by #71107.

[jordi-star]

Awesome, thanks for letting me know!