### Godot version

Beta 17, master

### System information

Windows 11

### Issue description

Godot gets a hard crash while attempting to code-complete for member `const` of a class.

### Steps to reproduce

```GDScript
enum E { V1 }

const e := E
```

And then type a `.` after the last `E`, which triggers code hints/auto-completion for subscripts based on `E` and causes a hard crash.

Does not happen for `var e := E.V1`.

### Minimal reproduction project

See above.
case GDScriptParser::DataType::VARIANT:
		case GDScriptParser::DataType::BUILTIN:
		case GDScriptParser::DataType::ENUM:
		case GDScriptParser::DataType::RESOLVING:
		case GDScriptParser::DataType::UNRESOLVED:
			break; 
	}
	switch (p_target.kind) {
		case GDScriptParser::DataType::NATIVE: {
			if (p_target.is_meta_type) {
				return ClassDB::is_parent_class(src_native, GDScriptNativeClass::get_class_static());
			}
			return ClassDB::is_parent_class(src_native, p_target.native_type);
		}
		case GDScriptParser::DataType::SCRIPT:
			if (p_target.is_meta_type) {
				return ClassDB::is_parent_class(src_native, p_target.script_type->get_class_name());
			}
			while (src_script.is_valid()) {
				if (src_script == p_target.script_type) {
					return true;
				}
				src_script = src_script->get_base_script();
			}
			return false;
		case GDScriptParser::DataType::CLASS:
			if (p_target.is_meta_type) {
				return ClassDB::is_parent_class(src_native, GDScript::get_class_static());
			}
			while (src_class != nullptr) {