Type-check Playwright E2E tests in CI

test/fx.ts

@@ -118,6 +118,7 @@ function tryGetStandardName(accountType: TestAccount) {
       : `${process.env.DE_TEST_ACCOUNT_PREFIX}-`;
     return `${actualPrefix}${accountType.toLocaleLowerCase()}`;
   }
+  return undefined;
 }
 
 // Maps a base API account type to its dedicated connection string (account key) account.
@@ -474,6 +475,7 @@ export enum CommandBarButton {
   ExecuteQuery = "Execute Query",
   UploadItem = "Upload Item",
   NewDocument = "New Document",
+  NewItem = "New Item",
   View = "View",
 }