### Godot version

4.0 beta 10

### System information

Windows 10

### Issue description

Godot crashes when i accidently name 2 items in an enum the same

EDIT:
The editor freeze for some seconds, then both editor- and console-window dissapear

### Steps to reproduce

Write

```gdscript
enum {
    A,
}
```

and then add a second line with another A:

```gdscript
enum {
    A,
    A # <- crash
}
```

Does not always immediatly happen if i copy&paste items.
Does not happen when i change the script in another editor and open the script in Godot.

### Minimal reproduction project

[enum.zip](https://github.com/godotengine/godot/files/10313759/enum.zip)

} else if (op_type.type_source == GDScriptParser::DataType::UNDETECTED && !assigned_is_variant) {
			
			downgrades_assignee = !assignee_is_hard;
			downgrades_assigned = !assigned_is_hard;
		}
	}
	p_assignment->set_datatype(op_type);
	if (assignee_is_variant) {
		if (!assignee_is_hard) {
			
			mark_node_unsafe(p_assignment);
		}
	} else {
		if (assignee_is_hard && !assigned_is_hard) {
			
			mark_node_unsafe(p_assignment);
			p_assignment->use_conversion_assign = true;
			downgrades_assigned = downgrades_assigned || (!assigned_is_variant && !is_type_compatible(assignee_type, op_type, true, p_assignment->assigned_value));
		} else if (compatible) {
			if (op_type.is_variant()) {
				
				mark_node_unsafe(p_assignment);
				if (assignee_is_hard) {
					
					p_assignment->use_conversion_assign = true;
				} else {
					
					downgrades_assignee = true;
				}
			} else if (!is_type_compatible(assignee_type, op_type, assignee_is_hard, p_assignment->assigned_value)) {