avoid cleanup for non-loadable assets

editor/import_dock.cpp

@@ -499,9 +499,12 @@ void ImportDock::_reimport_attempt() {
 
 		String imported_with = config->get_value("remap", "importer");
 		if (imported_with != importer_name) {
-			need_cleanup.push_back(params->paths[i]);
-			if (_find_owners(EditorFileSystem::get_singleton()->get_filesystem(), params->paths[i])) {
-				used_in_resources = true;
+			Ref<Resource> resource = ResourceLoader::load(params->paths[i]);
+			if (resource.is_valid()) {
+				need_cleanup.push_back(params->paths[i]);
+				if (_find_owners(EditorFileSystem::get_singleton()->get_filesystem(), params->paths[i])) {
+					used_in_resources = true;
+				}
 			}
 		}
 	}