### 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.
if (singl_parser.is_valid()) {
								Error err = singl_parser->raise_status(GDScriptParserRef::INHERITANCE_SOLVED);
								if (err == OK) {
									result = type_from_metatype(singl_parser->get_parser()->head->get_datatype());
								}
							}
						}
					}
				}
			}
			result.is_constant = true;
			p_identifier->set_datatype(result);
			return;
		}
	}
	if (GDScriptLanguage::get_singleton()->has_any_global_constant(name)) {
		Variant constant = GDScriptLanguage::get_singleton()->get_any_global_constant(name);
		p_identifier->set_datatype(type_from_variant(constant, p_identifier));
		p_identifier->is_constant = true;
		p_identifier->reduced_value = constant;
		return;
	}
	
	
	if (GDScriptUtilityFunctions::function_exists(name)) {
		push_error(vformat(R"(Built-in function "%s" cannot be used as an identifier.)", name), p_identifier);
	} else {
#ifdef TOOLS_ENABLED
#ifndef DISABLE_DEPRECATED
		String rename_hint = String();