### Godot version

4.1.dev (dc625bcbfc5b587ba8867481ee7a1f6a567c25d0)

### System information

Mageia 9, Linux

### Issue description

When importing a project in current `master`, the following error is raised for each asset that gets imported:
```
Attempting to parent and popup a dialog that already has a parent.
```

It seems to be raised once per asset, caused by the progress dialog.

CC @bruvzg

### Steps to reproduce

- Import a new project in Godot that contains importable assets, e.g. https://github.com/RPicster/godot4-demo-desert-light

### Minimal reproduction project

See above.
_THREAD_SAFE_METHOD_
	for (const KeyValue<String, int> &E : updates) {
		if (tasks.has(E.key)) {
			_task_step(E.key, E.value);
		}
	}
	updates.clear();
}
void BackgroundProgress::_task_step(const String &p_task, int p_step) {
	_THREAD_SAFE_METHOD_
	ERR_FAIL_COND(!tasks.has(p_task));
	Task &t = tasks[p_task];
	if (p_step < 0) {
		t.progress->set_value(t.progress->get_value() + 1);
	} else {
		t.progress->set_value(p_step);
	}
}
void BackgroundProgress::_end_task(const String &p_task) {
	_THREAD_SAFE_METHOD_
	ERR_FAIL_COND(!tasks.has(p_task));
	Task &t = tasks[p_task];
	memdelete(t.hb);
	tasks.erase(p_task);
}
void BackgroundProgress::_bind_methods() {