### 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.
Error err = resolve_class_inheritance(look_class, p_class);
							if (err) {
								return err;
							}
						}
						base = look_class->get_datatype();
						found = true;
						break;
					}
					if (look_class->has_member(name)) {
						resolve_class_member(look_class, name, p_class);
						base = look_class->get_member(name).get_datatype();
						found = true;
						break;
					}
				}
				if (!found) {
					push_error(vformat(R"(Could not find base class "%s".)", name), p_class);
					return ERR_PARSE_ERROR;
				}
			}
		}
		for (int index = extends_index; index < p_class->extends.size(); index++) {
			if (base.kind != GDScriptParser::DataType::CLASS) {
				push_error(R"(Super type "%s" is not a GDScript. Cannot get nested types.)", p_class);
				return ERR_PARSE_ERROR;
			}
			
			GDScriptParser::IdentifierNode *id = parser->alloc_node<GDScriptParser::IdentifierNode>();
			id->name = p_class->extends[index];