GDScript: Don't optimize division and modulo on debug

[vnen]

Since the validated operators don't have checks for division by zero, use the regular evaluator in debug which has those checks.

Fix #83308

[bitsawer]

I wonder if we should keep the zero division check in release builds, too. It will probably affect performance somewhat, but a full crash on some platforms for a reasonably common scripting language division error is kind of harsh. Even on platforms where it doesn't crash it is still undefined behavior.

Another similar division issue we might have to guard against is division of large (near INT64_MAX) negative value by -1. Warning, this will currently freeze the editor if this is even pasted into a .gd file, at least on Windows:

print(-9223372036854775808 / -1)

While probably not a common situation, it might be used as denial-of-service attack for example against server code that is not prepared for inputs like these.

[vnen]

@bitsawer this can be discussed but since this PR in particular is a bugfix, I prefer to keep the current behavior.

[bitsawer]

I agree the other division and modulo issue(s) can be handled in a separate PR if needed.

I'm not that familiar with the GDScript inner workings, so when you mentioned you prefer to "keep the current behavior", does that mean that division by integer zero will still crash the app when run on a release template build, but not in a debug build? Or does this PR fix both cases?

[vnen]

I'm not that familiar with the GDScript inner workings, so when you mentioned you prefer to "keep the current behavior", does that mean that division by integer zero will still crash the app when run on a release template build, but not in a debug build? Or does this PR fix both cases?

Division by zero crashes the release export. It has always been like this, even in 3.x. This PR makes it not crash only on debug.

[akien-mga]

Looks good.

Let's evaluate the impact of release-mode checks for this in 4.3.

[akien-mga]

Thanks!