### 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
switch (p_what) {
		case NOTIFICATION_ENTER_TREE: {
			EditorNode::get_singleton()->connect("stop_pressed", callable_mp(this, &ScriptEditor::_editor_stop));
			EditorNode::get_singleton()->connect("script_add_function_request", callable_mp(this, &ScriptEditor::_add_callback));
			EditorNode::get_singleton()->connect("resource_saved", callable_mp(this, &ScriptEditor::_res_saved_callback));
			EditorNode::get_singleton()->connect("scene_saved", callable_mp(this, &ScriptEditor::_scene_saved_callback));
			FileSystemDock::get_singleton()->connect("files_moved", callable_mp(this, &ScriptEditor::_files_moved));
			FileSystemDock::get_singleton()->connect("file_removed", callable_mp(this, &ScriptEditor::_file_removed));
			script_list->connect("item_selected", callable_mp(this, &ScriptEditor::_script_selected));
			members_overview->connect("item_selected", callable_mp(this, &ScriptEditor::_members_overview_selected));
			help_overview->connect("item_selected", callable_mp(this, &ScriptEditor::_help_overview_selected));
			script_split->connect("dragged", callable_mp(this, &ScriptEditor::_split_dragged));
			list_split->connect("dragged", callable_mp(this, &ScriptEditor::_split_dragged));
			EditorSettings::get_singleton()->connect("settings_changed", callable_mp(this, &ScriptEditor::_editor_settings_changed));
			EditorFileSystem::get_singleton()->connect("filesystem_changed", callable_mp(this, &ScriptEditor::_filesystem_changed));
			_editor_settings_changed();
			[[fallthrough]];
		}
		case NOTIFICATION_TRANSLATION_CHANGED:
		case NOTIFICATION_LAYOUT_DIRECTION_CHANGED:
		case NOTIFICATION_THEME_CHANGED: {
			help_search->set_icon(get_theme_icon(SNAME("HelpSearch"), SNAME("EditorIcons")));
			site_search->set_icon(get_theme_icon(SNAME("ExternalLink"), SNAME("EditorIcons")));
			if (is_layout_rtl()) {
				script_forward->set_icon(get_theme_icon(SNAME("Back"), SNAME("EditorIcons")));
				script_back->set_icon(get_theme_icon(SNAME("Forward"), SNAME("EditorIcons")));
			} else {
				script_forward->set_icon(get_theme_icon(SNAME("Forward"), SNAME("EditorIcons")));