fix(app-check)!: options is required in initializeAppCheck matching firebase-js-sdk

Require AppCheckOptions at the modular entry point and reject missing
options before native initialization. Document the stricter parameter in
compare-types; add runtime and type-test coverage.

Author: mikehardy

.github/scripts/compare-types/configs/app-check.ts

@@ -89,7 +89,7 @@ const config: PackageConfig = {
     {
       name: 'initializeAppCheck',
       reason:
-        'RN Firebase returns `Promise<AppCheck>` because App Check initialization crosses the native bridge, whereas the firebase-js-sdk returns `AppCheck` synchronously.',
+        'RN Firebase returns `Promise<AppCheck>` because App Check initialization crosses the native bridge, whereas the firebase-js-sdk returns `AppCheck` synchronously. The `options` argument is required on RN Firebase because native initialization always needs a configured provider; the firebase-js-sdk declaration marks it optional even though a provider is required in practice.',
     },
     {
       name: 'AppCheckOptions',

packages/app-check/__tests__/appcheck.test.ts

@@ -20,6 +20,12 @@ describe('appCheck()', function () {
       expect(initializeAppCheck).toBeDefined();
     });
 
+    it('`initializeAppCheck` rejects missing options', async function () {
+      await expect(initializeAppCheck(undefined, undefined as any)).rejects.toThrow(
+        'Invalid configuration: no options defined.',
+      );
+    });
+
     it('`getToken` function is properly exposed to end user', function () {
       expect(getToken).toBeDefined();
     });

packages/app-check/lib/index.ts

@@ -18,8 +18,8 @@
 import {
   isBoolean,
   isIOS,
-  isString,
   isObject,
+  isString,
   isUndefined,
   isOther,
   parseListenerOrObserver,
@@ -255,11 +255,14 @@ function getModularAppCheck(app?: FirebaseApp): AppCheck {
 }
 
 export async function initializeAppCheck(
-  app?: FirebaseApp,
-  options?: AppCheckOptions,
+  app: FirebaseApp | undefined,
+  options: AppCheckOptions,
 ): Promise<AppCheck> {
+  if (!isObject(options)) {
+    throw new Error('Invalid configuration: no options defined.');
+  }
   const appCheck = getModularAppCheck(app);
-  await (appCheck as AppCheckInternal).initializeAppCheck(options as AppCheckOptions);
+  await (appCheck as AppCheckInternal).initializeAppCheck(options);
   return appCheck;
 }
 

packages/app-check/type-test.ts

@@ -25,6 +25,9 @@ initializeAppCheck(getApp(), options).then((instance: AppCheck) => {
   console.log(instance.app.name);
 });
 
+// @ts-expect-error options is required for App Check initialization
+initializeAppCheck(getApp());
+
 getToken(appCheck).then((result: AppCheckTokenResult) => {
   console.log(result.token);
 });