### 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.
break;
							case 3:
								reduced = Vector3i(args[0], args[1], args[2]);
								break;
						}
						p_for->list->is_constant = true;
						p_for->list->reduced_value = reduced;
					}
				}
				if (p_for->list->is_constant) {
					p_for->list->set_datatype(type_from_variant(p_for->list->reduced_value, p_for->list));
				} else {
					GDScriptParser::DataType list_type;
					list_type.type_source = GDScriptParser::DataType::ANNOTATED_EXPLICIT;
					list_type.kind = GDScriptParser::DataType::BUILTIN;
					list_type.builtin_type = Variant::ARRAY;
					p_for->list->set_datatype(list_type);
				}
			}
		}
	}
	GDScriptParser::DataType variable_type;
	if (list_resolved) {
		variable_type.type_source = GDScriptParser::DataType::ANNOTATED_INFERRED;
		variable_type.kind = GDScriptParser::DataType::BUILTIN;
		variable_type.builtin_type = Variant::INT;
	} else if (p_for->list) {
		resolve_node(p_for->list, false);
		GDScriptParser::DataType list_type = p_for->list->get_datatype();
		if (!list_type.is_hard_type()) {