core/generation: use deleteLater() to delete file watchers

Should fix crashes similar to those in FileView.

Author: outfoxxed

src/core/generation.cpp

@@ -192,7 +192,7 @@ void EngineGeneration::setWatchingFiles(bool watching) {
 		}
 	} else {
 		if (this->watcher != nullptr) {
-			delete this->watcher;
+			this->watcher->deleteLater();
 			this->watcher = nullptr;
 		}
 	}