Test fix

Author: schmidt-sebastian

packages/firestore/test/integration/api/database.test.ts

@@ -1162,8 +1162,8 @@ apiDescribe('Database', (persistence: boolean) => {
       await withTestDoc(persistence, async docRef => {
         const firestore = docRef.firestore;
         const expectedError =
-          'Persistence can only be cleared before a Firestore instance is' +
-          'initialized or after it is terminated';
+          'Persistence can only be cleared before a Firestore instance is ' +
+          'initialized or after it is terminated.';
         if (usesModularApi()) {
           // The modular API throws an exception rather than rejecting the
           // Promise, which matches our overall handling of API call violations.