### Godot version

4.0-stable

### System information

Fedora Linux 37

### Issue description

When a plugin adds a bottom panel to the editor with `add_control_to_bottom_panel(control: Control, title: String)`, if the bottom panel scene contains a `SubViewport` with a `Camera2D`, the editor will crash with the following back trace:

```
================================================================
handle_crash: Program crashed with signal 11
Engine version: Godot Engine v4.0.stable.official (92bee43adba8d2401ef40e2480e53087bcb1eaf1)
Dumping the backtrace. Please include this when reporting the bug to the project developer.
[1] /lib64/libc.so.6(+0x3cb20) [0x7f899af8fb20] (??:0)
[2] /home/max/godot/Godot_v4.0-stable_linux.x86_64() [0x312ab03] (??:0)
[3] /home/max/godot/Godot_v4.0-stable_linux.x86_64() [0x4568594] (??:0)
[4] /home/max/godot/Godot_v4.0-stable_linux.x86_64() [0x2b594c9] (??:0)
[5] /home/max/godot/Godot_v4.0-stable_linux.x86_64() [0x2b5b552] (??:0)
[6] /home/max/godot/Godot_v4.0-stable_linux.x86_64() [0x2b5b701] (??:0)
[7] /home/max/godot/Godot_v4.0-stable_linux.x86_64() [0x2b5b7eb] (??:0)
[8] /home/max/godot/Godot_v4.0-stable_linux.x86_64() [0x2b2aa46] (??:0)
[9] /home/max/godot/Godot_v4.0-stable_linux.x86_64() [0x128ca03] (??:0)
[10] /home/max/godot/Godot_v4.0-stable_linux.x86_64() [0x118b77f] (??:0)
[11] /home/max/godot/Godot_v4.0-stable_linux.x86_64() [0x458c73b] (??:0)
[12] /home/max/godot/Godot_v4.0-stable_linux.x86_64() [0x43c69a4] (??:0)
[13] /home/max/godot/Godot_v4.0-stable_linux.x86_64() [0x4b84d75] (??:0)
[14] /home/max/godot/Godot_v4.0-stable_linux.x86_64() [0x45dac77] (??:0)
[15] /home/max/godot/Godot_v4.0-stable_linux.x86_64() [0x2bd1cc8] (??:0)
[16] /home/max/godot/Godot_v4.0-stable_linux.x86_64() [0xebffb6] (??:0)
[17] /home/max/godot/Godot_v4.0-stable_linux.x86_64() [0xe027f3] (??:0)
[18] /lib64/libc.so.6(+0x27510) [0x7f899af7a510] (??:0)
[19] /lib64/libc.so.6(__libc_start_main+0x89) [0x7f899af7a5c9] (??:0)
[20] /home/max/godot/Godot_v4.0-stable_linux.x86_64() [0xe2286e] (??:0)
-- END OF BACKTRACE --
================================================================
```

The only time I have found this error to not occur is if you enable said plugin when the bottom panel scene is already open in the editor

### Steps to reproduce

1. Create a new plugin
3. Create a new scene with a control node root
4. Add a `SubViewport` as a child of the scene
5. Add a `Camera2D` as a child of the `SubViewport`
6. Use `add_control_to_bottom_panel` in the plugin script to add said scene to the bottom panel
7. Have said plugin enabled when said scene is not loaded in the editor

To trigger the crash in the minimal reproduction project, make sure the `bottom_panel_example.tscn` scene is closed then go to Project -> Project Settings -> Plugins and click enable next to `example_plugin`

### Minimal reproduction project

[MinimalReproductionProject.zip](https://github.com/godotengine/godot/files/11224815/MinimalReproductionProject.zip)

ERR_FAIL_INDEX((int)p_side, 4);
	limit[p_side] = p_limit;
	Point2 old_smoothed_camera_pos = smoothed_camera_pos;
	_update_scroll();
	smoothed_camera_pos = old_smoothed_camera_pos;
}
int Camera2D::get_limit(Side p_side) const {
	ERR_FAIL_INDEX_V((int)p_side, 4, 0);
	return limit[p_side];
}
void Camera2D::set_limit_smoothing_enabled(bool enable) {
	limit_smoothing_enabled = enable;
	_update_scroll();
}
bool Camera2D::is_limit_smoothing_enabled() const {
	return limit_smoothing_enabled;
}
void Camera2D::set_drag_margin(Side p_side, real_t p_drag_margin) {
	ERR_FAIL_INDEX((int)p_side, 4);
	drag_margin[p_side] = p_drag_margin;
	queue_redraw();
}
real_t Camera2D::get_drag_margin(Side p_side) const {
	ERR_FAIL_INDEX_V((int)p_side, 4, 0);
	return drag_margin[p_side];
}
Vector2 Camera2D::get_camera_position() const {