### Godot version

4.1.3 stable.arch_linux

### System information

Artix Linux Godot v4.1.3 stable.arch_linux

### Issue description

![2023-11-14T16:29:28,788232528+01:00](https://github.com/godotengine/godot/assets/92468390/a79027e2-1539-4ca9-9369-978c32dea26d)
Both "Target Surface:" and "Source Mesh:" accept non Node3D nodes which doesn't really make any sense as they need 3D geometry to function.

### Steps to reproduce

1. Add a MultiMeshInstance3D
2. Add a Node that doesn't inherit Node3D
3. Open the "Populate Surface" menu and click the right button of either "Target Surface:" or "Source Mesh:"

### Minimal reproduction project

N/A
hbc->add_child(surface_source);
	surface_source->set_h_size_flags(SIZE_EXPAND_FILL);
	Button *b = memnew(Button);
	hbc->add_child(b);
	b->set_text("..");
	b->connect("pressed", callable_mp(this, &MultiMeshEditor::_browse).bind(false));
	vbc->add_margin_child(TTR("Target Surface:"), hbc);
	hbc = memnew(HBoxContainer);
	mesh_source = memnew(LineEdit);
	hbc->add_child(mesh_source);
	mesh_source->set_h_size_flags(SIZE_EXPAND_FILL);
	b = memnew(Button);
	hbc->add_child(b);
	b->set_text("..");
	vbc->add_margin_child(TTR("Source Mesh:"), hbc);
	b->connect("pressed", callable_mp(this, &MultiMeshEditor::_browse).bind(true));
	populate_axis = memnew(OptionButton);
	populate_axis->add_item(TTR("X-Axis"));
	populate_axis->add_item(TTR("Y-Axis"));
	populate_axis->add_item(TTR("Z-Axis"));
	populate_axis->select(2);
	vbc->add_margin_child(TTR("Mesh Up Axis:"), populate_axis);
	populate_rotate_random = memnew(HSlider);
	populate_rotate_random->set_max(1);
	populate_rotate_random->set_step(0.01);
	vbc->add_margin_child(TTR("Random Rotation:"), populate_rotate_random);
	populate_tilt_random = memnew(HSlider);
	populate_tilt_random->set_max(1);
	populate_tilt_random->set_step(0.01);
	vbc->add_margin_child(TTR("Random Tilt:"), populate_tilt_random);