Firestore increment crashes app on Android

gistfile1.txt

D/AndroidRuntime(10123): Shutting down VM
E/AndroidRuntime(10123): FATAL EXCEPTION: main
E/AndroidRuntime(10123): Process: app, PID: 10123
E/AndroidRuntime(10123): java.lang.RuntimeException: Internal error in Firestore (19.0.0).
E/AndroidRuntime(10123): 	at com.google.firebase.firestore.util.AsyncQueue.lambda$panic$5(com.google.firebase:firebase-firestore@@19.0.0:379)
E/AndroidRuntime(10123): 	at com.google.firebase.firestore.util.AsyncQueue$$Lambda$5.run(Unknown Source:2)
E/AndroidRuntime(10123): 	at android.os.Handler.handleCallback(Handler.java:873)
E/AndroidRuntime(10123): 	at android.os.Handler.dispatchMessage(Handler.java:99)
E/AndroidRuntime(10123): 	at android.os.Looper.loop(Looper.java:193)
E/AndroidRuntime(10123): 	at android.app.ActivityThread.main(ActivityThread.java:6669)
E/AndroidRuntime(10123): 	at java.lang.reflect.Method.invoke(Native Method)
E/AndroidRuntime(10123): 	at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
E/AndroidRuntime(10123): 	at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)
E/AndroidRuntime(10123): Caused by: java.lang.AssertionError: INTERNAL ASSERTION FAILED: Encoded field value should not be null.
E/AndroidRuntime(10123): 	at com.google.firebase.firestore.util.Assert.fail(com.google.firebase:firebase-firestore@@19.0.0:46)
E/AndroidRuntime(10123): 	at com.google.firebase.firestore.util.Assert.hardAssert(com.google.firebase:firebase-firestore@@19.0.0:31)
E/AndroidRuntime(10123): 	at com.google.firebase.firestore.remote.RemoteSerializer.encodeValue(com.google.firebase:firebase-firestore@@19.0.0:263)
E/AndroidRuntime(10123): 	at com.google.firebase.firestore.remote.RemoteSerializer.encodeDocument(com.google.firebase:firebase-firestore@@19.0.0:389)
E/AndroidRuntime(10123): 	at com.google.firebase.firestore.remote.RemoteSerializer.encodeMutation(com.google.firebase:firebase-firestore@@19.0.0:436)
E/AndroidRuntime(10123): 	at com.google.firebase.firestore.local.LocalSerializer.encodeMutationBatch(com.google.firebase:firebase-firestore@@19.0.0:169)
E/AndroidRuntime(10123): 	at com.google.firebase.firestore.local.SQLiteMutationQueue.addMutationBatch(com.google.firebase:firebase-firestore@@19.0.0:188)
E/AndroidRuntime(10123): 	at com.google.firebase.firestore.local.LocalStore.lambda$writeLocally$1(com.google.firebase:firebase-firestore@@19.0.0:237)
E/AndroidRuntime(10123): 	at com.google.firebase.firestore.local.LocalStore$$Lambda$2.get(Unknown Source:8)
E/AndroidRuntime(10123): 	at com.google.firebase.firestore.local.SQLitePersistence.runTransaction(com.google.firebase:firebase-firestore@@19.0.0:195)
E/AndroidRuntime(10123): 	at com.google.firebase.firestore.local.LocalStore.writeLocally(com.google.firebase:firebase-firestore@@19.0.0:201)
E/AndroidRuntime(10123): 	at com.google.firebase.firestore.core.SyncEngine.writeMutations(com.google.firebase:firebase-firestore@@19.0.0:227)
E/AndroidRuntime(10123): 	at com.google.firebase.firestore.core.FirestoreClient.lambda$write$11(com.google.firebase:firebase-firestore@@19.0.0:200)
E/AndroidRuntime(10123): 	at com.google.firebase.firestore.core.FirestoreClient$$Lambda$11.run(Unknown Source:6)
E/AndroidRuntime(10123): 	at com.google.firebase.firestore.util.AsyncQueue.lambda$enqueue$4(com.google.firebase:firebase-firestore@@19.0.0:311)
E/AndroidRuntime(10123): 	at com.google.firebase.firestore.util.AsyncQueue$$Lambda$4.call(Unknown Source:2)
E/AndroidRuntime(10123): 	at com.google.firebase.firestore.util.AsyncQueue.lambda$enqueue$3(com.google.firebase:firebase-firestore@@19.0.0:287)
E/AndroidRuntime(10123): 	at com.google.firebase.firestore.util.AsyncQueue$$Lambda$3.run(Unknown Source:4)
E/AndroidRuntime(10123): 	at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:458)
E/AndroidRuntime(10123): 	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
E/AndroidRuntime(10123): 	at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:301)
E/AndroidRuntime(10123): 	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167)
E/AndroidRuntime(10123): 	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641)
E/AndroidRuntime(10123): 	at com.google.firebase.firestore.util.AsyncQueue$DelayedStartFactory.run(com.google.firebase:firebase-firestore@@19.0.0:205)
E/AndroidRuntime(10123): 	at java.lang.Thread.run(Thread.java:764)