Fix incorrect script check

[quirkylemon]

I think the issue was caused by 'script.is_valid' returning true but the path being empty.
fixes #90467

[dalexeev]

Sorry, I think this is an incorrect solution. You are using Array[BaseNativeType] instead of Array[PathlessScriptType], but these types are incompatible with each other in both directions. Even if this "fixes" it for the debugger (see also #90751 (comment)), binary serialization is not just for the debugger. Error reporting when the script has an empty path was intentional in #78219.

The cleanest solution I can imagine would be to introduce fully qualified type names (FQTN), which would allow any type to be universally and uniquely identified:

FQTN proposal fragment

• ClassDB types (Object, Node, etc.).
• Global script classes. Must be unique for all languages. Namespaces are possible, in which case some separator is used (., :: or something else).
• Unnamed script classes in the res:// file system (like "res://script.gd").
• Scripts created on the fly (like "gdscript://12345"). The protocol defines the scripting language, followed by the script instance id.
• Enumerations, inner classes and structures use .. For example GlobalClass.InnerClass or "res://script.gd".InnerClass.MyEnum.

But it's more complicated than it seems. We can't just introduce a new format in one place without thinking about others. So for now I would look for other workarounds, on the debugger / editor UI side.

[akien-mga]

Superseded by #94379. Thanks for the contribution!