### 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
int line = p_script->get_member_line(p_method);
	if (line == -1) {
		return false;
	}
	return edit(p_script, line, 0);
}
void ScriptEditor::set_live_auto_reload_running_scripts(bool p_enabled) {
	auto_reload_running_scripts = p_enabled;
}
void ScriptEditor::_help_search(String p_text) {
	help_search_dialog->popup_dialog(p_text);
}
void ScriptEditor::_open_script_request(const String &p_path) {
	Ref<Script> scr = ResourceLoader::load(p_path);
	if (scr.is_valid()) {
		script_editor->edit(scr, false);
		return;
	}
	Error err;
	Ref<TextFile> text_file = script_editor->_load_text_file(p_path, &err);
	if (text_file.is_valid()) {
		script_editor->edit(text_file, false);
		return;
	}
}
void ScriptEditor::register_syntax_highlighter(const Ref<EditorSyntaxHighlighter> &p_syntax_highlighter) {