### 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.
member.m_enum->set_datatype(enum_type);
				member.m_enum->dictionary = dictionary;
				
				for (GDScriptParser::AnnotationNode *&E : member.m_enum->annotations) {
					resolve_annotation(E);
					E->apply(parser, member.m_enum);
				}
			} break;
			case GDScriptParser::ClassNode::Member::FUNCTION:
				resolve_function_signature(member.function, p_source);
				break;
			case GDScriptParser::ClassNode::Member::ENUM_VALUE: {
				member.enum_value.identifier->set_datatype(resolving_datatype);
				if (member.enum_value.custom_value) {
					check_class_member_name_conflict(p_class, member.enum_value.identifier->name, member.enum_value.custom_value);
					const GDScriptParser::EnumNode *prev_enum = current_enum;
					current_enum = member.enum_value.parent_enum;
					reduce_expression(member.enum_value.custom_value);
					current_enum = prev_enum;
					if (!member.enum_value.custom_value->is_constant) {
						push_error(R"(Enum values must be constant.)", member.enum_value.custom_value);
					} else if (member.enum_value.custom_value->reduced_value.get_type() != Variant::INT) {
						push_error(R"(Enum values must be integers.)", member.enum_value.custom_value);
					} else {
						member.enum_value.value = member.enum_value.custom_value->reduced_value;
						member.enum_value.resolved = true;
					}
				} else {
					check_class_member_name_conflict(p_class, member.enum_value.identifier->name, member.enum_value.parent_enum);
					if (member.enum_value.index > 0) {