### 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
file_dialog_option = -1;
		} break;
		case FILE_SAVE_AS: {
			ScriptEditorBase *current = _get_current_editor();
			if (current) {
				Ref<Resource> resource = current->get_edited_resource();
				String path = ProjectSettings::get_singleton()->localize_path(p_file);
				Error err = _save_text_file(resource, path);
				if (err != OK) {
					EditorNode::get_singleton()->show_accept(TTR("Error saving file!"), TTR("OK"));
					return;
				}
				resource->set_path(path);
				_update_script_names();
			}
		} break;
		case THEME_SAVE_AS: {
			if (!EditorSettings::get_singleton()->save_text_editor_theme_as(p_file)) {
				EditorNode::get_singleton()->show_warning(TTR("Error while saving theme."), TTR("Error Saving"));
			}
		} break;
		case THEME_IMPORT: {
			if (!EditorSettings::get_singleton()->import_text_editor_theme(p_file)) {
				EditorNode::get_singleton()->show_warning(TTR("Error importing theme."), TTR("Error Importing"));
			}
		} break;
	}
	file_dialog_option = -1;
}
Ref<Script> ScriptEditor::_get_current_script() {