### Godot version

5ee983188de97ae027f9b9c1443438063f708a7e

### System information

Windows 11

### Issue description

Godot editor will throw an error and fail to generate preview icons for terrain tiles which use a base image which is not RGBA8 format.
`core\io\image.cpp:2788 - Condition "format != p_src->format" is true.`

### Steps to reproduce

- Import a non-RGBA8 image into Godot.
- Create a TileMap
- Create an associated TileSet
- Create a terrain for this tileset
- Add the image as an atlas
- Go to the paint tab
- Paint the terrain on the TileSet
- An error will occur any time terrains are edited in the TileSet editor or selected in the TileMap editor terrain tab.

### Minimal reproduction project

[tileset_terrain_bug.zip](https://github.com/godotengine/godot/files/13264213/tileset_terrain_bug.zip)

for (int i = 0; i < scenes_ids.size(); i++) {
		p_list->push_back(PropertyInfo(Variant::OBJECT, vformat("%s/%d/%s", PNAME("scenes"), scenes_ids[i], PNAME("scene")), PROPERTY_HINT_RESOURCE_TYPE, "TileSetScenesCollectionSource"));
		PropertyInfo property_info = PropertyInfo(Variant::BOOL, vformat("%s/%d/%s", PNAME("scenes"), scenes_ids[i], PNAME("display_placeholder")));
		if (scenes[scenes_ids[i]].display_placeholder == false) {
			property_info.usage ^= PROPERTY_USAGE_STORAGE;
		}
		p_list->push_back(property_info);
	}
}
void TileSetScenesCollectionSource::_bind_methods() {
	ClassDB::bind_method(D_METHOD("get_scene_tiles_count"), &TileSetScenesCollectionSource::get_scene_tiles_count);
	ClassDB::bind_method(D_METHOD("get_scene_tile_id", "index"), &TileSetScenesCollectionSource::get_scene_tile_id);
	ClassDB::bind_method(D_METHOD("has_scene_tile_id", "id"), &TileSetScenesCollectionSource::has_scene_tile_id);
	ClassDB::bind_method(D_METHOD("create_scene_tile", "packed_scene", "id_override"), &TileSetScenesCollectionSource::create_scene_tile, DEFVAL(INVALID_TILE_ALTERNATIVE));
	ClassDB::bind_method(D_METHOD("set_scene_tile_id", "id", "new_id"), &TileSetScenesCollectionSource::set_scene_tile_id);
	ClassDB::bind_method(D_METHOD("set_scene_tile_scene", "id", "packed_scene"), &TileSetScenesCollectionSource::set_scene_tile_scene);
	ClassDB::bind_method(D_METHOD("get_scene_tile_scene", "id"), &TileSetScenesCollectionSource::get_scene_tile_scene);
	ClassDB::bind_method(D_METHOD("set_scene_tile_display_placeholder", "id", "display_placeholder"), &TileSetScenesCollectionSource::set_scene_tile_display_placeholder);
	ClassDB::bind_method(D_METHOD("get_scene_tile_display_placeholder", "id"), &TileSetScenesCollectionSource::get_scene_tile_display_placeholder);
	ClassDB::bind_method(D_METHOD("remove_scene_tile", "id"), &TileSetScenesCollectionSource::remove_scene_tile);
	ClassDB::bind_method(D_METHOD("get_next_scene_tile_id"), &TileSetScenesCollectionSource::get_next_scene_tile_id);
}
void TileData::set_tile_set(const TileSet *p_tile_set) {
	tile_set = p_tile_set;
	notify_tile_data_properties_should_change();
}
void TileData::notify_tile_data_properties_should_change() {