### Godot version

3.5.1mono

### System information

windows10

### Issue description

Error message
 scene/main/node.cpp:1362 - Index p_index = 0 is out of bounds (data.children.size() = 0).
 scene/main/node.cpp:397 - Parameter "p_child" is null.
 scene/gui/tab_container.cpp:593 - Index p_current = 0 is out of bounds (get_tab_count() = 0).
See "Steps to reproduce for details"

### Steps to reproduce

Set an external text editor
Create a script
Drop the script to the built-in text editor like this image:
![image](https://user-images.githubusercontent.com/119792950/209504041-039f2620-5e42-4c0f-8c41-cd24486fb3d2.png)
And got error message:
 scene/main/node.cpp:1362 - Index p_index = 0 is out of bounds (data.children.size() = 0).
 scene/main/node.cpp:397 - Parameter "p_child" is null.
 scene/gui/tab_container.cpp:593 - Index p_current = 0 is out of bounds (get_tab_count() = 0).

### Minimal reproduction project

An empty project
ERR_FAIL_COND(p_event.is_null());
	if (!is_visible_in_tree() || !p_event->is_pressed() || p_event->is_echo()) {
		return;
	}
	if (ED_IS_SHORTCUT("script_editor/next_script", p_event)) {
		if (script_list->get_item_count() > 1) {
			int next_tab = script_list->get_current() + 1;
			next_tab %= script_list->get_item_count();
			_go_to_tab(script_list->get_item_metadata(next_tab));
			_update_script_names();
		}
		accept_event();
	}
	if (ED_IS_SHORTCUT("script_editor/prev_script", p_event)) {
		if (script_list->get_item_count() > 1) {
			int next_tab = script_list->get_current() - 1;
			next_tab = next_tab >= 0 ? next_tab : script_list->get_item_count() - 1;
			_go_to_tab(script_list->get_item_metadata(next_tab));
			_update_script_names();
		}
		accept_event();
	}
	if (ED_IS_SHORTCUT("script_editor/window_move_up", p_event)) {