### 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
_update_modified_scripts_for_external_editor();
}
void ScriptEditor::notify_script_close(const Ref<Script> &p_script) {
	emit_signal(SNAME("script_close"), p_script);
}
void ScriptEditor::notify_script_changed(const Ref<Script> &p_script) {
	emit_signal(SNAME("editor_script_changed"), p_script);
}
void ScriptEditor::get_breakpoints(List<String> *p_breakpoints) {
	HashSet<String> loaded_scripts;
	for (int i = 0; i < tab_container->get_tab_count(); i++) {
		ScriptEditorBase *se = Object::cast_to<ScriptEditorBase>(tab_container->get_tab_control(i));
		if (!se) {
			continue;
		}
		Ref<Script> scr = se->get_edited_resource();
		if (scr == nullptr) {
			continue;
		}
		String base = scr->get_path();
		loaded_scripts.insert(base);
		if (base.begins_with("local://") || base.is_empty()) {
			continue;
		}
		PackedInt32Array bpoints = se->get_breakpoints();
		for (int j = 0; j < bpoints.size(); j++) {