Firestore error after null safety migration

[John Boudreaux]

My application is working fine before null safety migration. Afterwards I get a runtime error when attempting to read a record, "Error: [cloud_firestore/unknown] Expected a value of type '((Object?) => Object)?', but got one of type '(Object) => Object?'"

I thought maybe I did something wrong in the migration, so I created a new application with just the minimum to reproduce. It worked fine on flutter >=2.7.0 but when I changed to >2.12.0 to enable null safety, the same error occurred. It is occurring on the read from the firestore collection:

var s = await FirebaseFirestore.instance

  .collection('cautions')

  .snapshots()

  .first;

 

[Suzuki Tomohiro]

Why is that “unknown”? No source file name or line number?

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[Chris Sells]

This sounds like an excellent bug to log at https://github.com/firebaseextended/flutterfire/issues

To view this discussion on the web visit https://groups.google.com/d/msgid/flutter-dev/CAHWORbrTEd_hvgivZSS0Fiu2c3rgxsi%3DX7vfLR71dcrZy9%3DUZA%40mail.gmail.com.

[John Boudreaux]

I should mention, this is a web application. Flutterfire seems to have some firestore for web special source files.

Here is the whole stack trace:

Error: [cloud_firestore/unknown] Expected a value of type '((Object?) => Object)?', but got one of type '(Object) => Object?'

at Object.throw_ [as throw] (http://localhost:54863/dart_sdk.js:5032:11)

at http://localhost:54863/packages/cloud_firestore_web/src/write_batch_web.dart.lib.js:397:19

at Object._checkAndCall (http://localhost:54863/dart_sdk.js:5237:16)

at Object.dcall (http://localhost:54863/dart_sdk.js:5242:17)

at Object._invokeErrorHandler (http://localhost:54863/dart_sdk.js:37273:19)

at _HandleErrorStream.new.[_handleError] (http://localhost:54863/dart_sdk.js:35175:19)

at _ForwardingStreamSubscription.new.[_handleError] (http://localhost:54863/dart_sdk.js:34993:38)

at _RootZone.runBinaryGuarded (http://localhost:54863/dart_sdk.js:37034:11)

at sendError (http://localhost:54863/dart_sdk.js:30966:26)

at _ForwardingStreamSubscription.new.[_sendError] (http://localhost:54863/dart_sdk.js:30983:11)

at _ForwardingStreamSubscription.new.[_addError] (http://localhost:54863/dart_sdk.js:30909:27)

at _ForwardingStreamSubscription.new.[_addError] (http://localhost:54863/dart_sdk.js:34968:25)

at Object._addErrorWithReplacement (http://localhost:54863/dart_sdk.js:37469:20)

at _MapStream.new.[_handleData] (http://localhost:54863/dart_sdk.js:35081:19)

at _ForwardingStreamSubscription.new.[_handleData] (http://localhost:54863/dart_sdk.js:34990:37)

at _RootZone.runUnaryGuarded (http://localhost:54863/dart_sdk.js:37018:11)

at _BroadcastSubscription.new.[_sendData] (http://localhost:54863/dart_sdk.js:30952:22)

at _BroadcastSubscription.new.[_add] (http://localhost:54863/dart_sdk.js:30901:26)

at _SyncBroadcastStreamController.new.[_sendData] (http://localhost:54863/dart_sdk.js:31595:34)

at _SyncBroadcastStreamController.new.add (http://localhost:54863/dart_sdk.js:31394:24)

at http://localhost:54863/packages/cloud_firestore_web/src/interop/utils/utils.dart.lib.js:535:30

at Object._checkAndCall (http://localhost:54863/dart_sdk.js:5237:16)

at Object.dcall (http://localhost:54863/dart_sdk.js:5242:17)

at Array.ret (http://localhost:54863/dart_sdk.js:57497:21)

at next (https://www.gstatic.com/firebasejs/7.20.0/firebase-firestore.js:1:280446)

at https://www.gstatic.com/firebasejs/7.20.0/firebase-firestore.js:1:228287

Application finished.

Exited (sigterm) 

[John Boudreaux]

I opened an issue on github. The moderators closed it as a duplicate even though I searched for this beforehand. Alas, there is an issue open #5050.

[John Boudreaux]

BTW, if you run it with 

```

flutter run --no-sound-null-safety 

```

It gets around them problem. So, we can still work while waiting on the fix.