### 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 (file_dialog_option) {
		case FILE_NEW_TEXTFILE: {
			Error err;
			{
				Ref<FileAccess> file = FileAccess::open(p_file, FileAccess::WRITE, &err);
				if (err) {
					EditorNode::get_singleton()->show_warning(TTR("Error writing TextFile:") + "\n" + p_file, TTR("Error!"));
					break;
				}
			}
			if (EditorFileSystem::get_singleton()) {
				if (textfile_extensions.has(p_file.get_extension())) {
					EditorFileSystem::get_singleton()->update_file(p_file);
				}
			}
			if (!open_textfile_after_create) {
				return;
			}
			[[fallthrough]];
		}
		case FILE_OPEN: {
			open_file(p_file);