### 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 (is_type_compatible(op_type, assignee_type)) {
						
						p_assignment->use_conversion_assign = true;
					} else {
						
						push_error(vformat(R"(Value of type "%s" cannot be assigned to a variable of type "%s".)", assigned_value_type.to_string(), assignee_type.to_string()), p_assignment->assigned_value);
					}
				} else {
					
					downgrades_assignee = true;
				}
			} else if (assignee_type.has_container_element_type() && !op_type.has_container_element_type()) {
				
				mark_node_unsafe(p_assignment);
			}
		}
	}
	if (downgrades_assignee) {
		downgrade_node_type_source(p_assignment->assignee);
	}
	if (downgrades_assigned) {
		downgrade_node_type_source(p_assignment->assigned_value);
	}
#ifdef DEBUG_ENABLED
	if (assignee_type.is_hard_type() && assignee_type.builtin_type == Variant::INT && assigned_value_type.builtin_type == Variant::FLOAT) {
		parser->push_warning(p_assignment->assigned_value, GDScriptWarning::NARROWING_CONVERSION);
	}
#endif
}
void GDScriptAnalyzer::reduce_await(GDScriptParser::AwaitNode *p_await) {