fix: LiveQuery server is not shut down properly when handleShutdown is called (#8491)

src/Adapters/Storage/Postgres/PostgresStorageAdapter.js

@@ -1194,7 +1194,9 @@ export class PostgresStorageAdapter implements StorageAdapter {
     const now = new Date().getTime();
     const helpers = this._pgp.helpers;
     debug('deleteAllClasses');
-
+    if (this._client?.$pool.ended) {
+      return;
+    }
     await this._client
       .task('delete-all-classes', async t => {
         try {