handles unstructured errors on redirect URLs

Author: Ivan164

Example/Auth/Tests/FIRPhoneAuthProviderTests.m

@@ -732,8 +732,7 @@ - (void)testVerifyPhoneNumberUIDelegateUnexpectedError {
 }
 
 /** @fn testVerifyPhoneNumberUIDelegateUnstructuredError
-    @brief Tests a invocation of @c verifyPhoneNumber:UIDelegate:completion: which results in an
-        invalid client ID.
+    @brief Tests a invocation of @c verifyPhoneNumber:UIDelegate:completion: which results in an error being surfaced due to an unexpected structure of the error response.
  */
 - (void)testVerifyPhoneNumberUIDelegateUnstructuredError {
   id mockBundle = OCMClassMock([NSBundle class]);

Firebase/Auth/Source/AuthProviders/Phone/FIRPhoneAuthProvider.m

@@ -267,7 +267,8 @@ - (NSString *)reCAPTCHATokenForURL:(NSURL *)URL error:(NSError **)error {
     if(errorDict[@"code"] && errorDict[@"message"]) {
       reason = [NSString stringWithFormat:@"[%@] - %@",errorDict[@"code"], errorDict[@"message"]];
     } else {
-      reason = @"An unknown error has occurred";
+      reason = [NSString StringWithFormat:@"An unknown error occurred with the following "
+                                "response: %@", deepLinkURL];
     }
     *error = [FIRAuthErrorUtils appVerificationUserInteractionFailureWithReason:reason];
   }