### 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.
return;
		}
		if (ClassDB::get_signal(native, name, &method_info)) {
			
			p_identifier->set_datatype(make_signal_type(method_info));
			p_identifier->source = GDScriptParser::IdentifierNode::INHERITED_VARIABLE;
			return;
		}
		if (ClassDB::has_enum(native, name)) {
			p_identifier->set_datatype(make_native_enum_type(name, native));
			p_identifier->source = GDScriptParser::IdentifierNode::MEMBER_CONSTANT;
			return;
		}
		bool valid = false;
		int64_t int_constant = ClassDB::get_integer_constant(native, name, &valid);
		if (valid) {
			p_identifier->is_constant = true;
			p_identifier->reduced_value = int_constant;
			p_identifier->source = GDScriptParser::IdentifierNode::MEMBER_CONSTANT;
			
			StringName enum_name = ClassDB::get_integer_constant_enum(native, name);
			if (enum_name != StringName()) {
				p_identifier->set_datatype(make_native_enum_type(enum_name, native, false));
			} else {
				p_identifier->set_datatype(type_from_variant(int_constant, p_identifier));
			}
		}
	}
}
void GDScriptAnalyzer::reduce_identifier(GDScriptParser::IdentifierNode *p_identifier, bool can_be_builtin) {