Very Important!!! Firebase Security Rules - Android App Crash on Sign Out

I have made a Journal app which uses Cloud Firestore and Firebase Auth.Everything was working great until I updated the security rules. After signout I come back to Login Activity and then immediately the app crashes and error is shown in previous page even after that activity is finished.Kindly help; Android Studio error message screenshot attached.

The App is crashing as soon as the user signs out

    private void getJournals(final Context ctx) {        final List<Journal> journalList=new ArrayList<>();        String currentUserId = currentUser.getUid();            collectionReference.whereEqualTo("userId",currentUserId)                   //line 182                    .addSnapshotListener(new EventListener<QuerySnapshot>() {                        @RequiresApi(api = Build.VERSION_CODES.N)                        @Override                        public void onEvent(@Nullable QuerySnapshot queryDocumentSnapshots,                                            @Nullable FirebaseFirestoreException error) {                            if (!queryDocumentSnapshots.isEmpty()) {                   //line 187                                for (QueryDocumentSnapshot snapshot : queryDocumentSnapshots) {                                    Journal journal = snapshot.toObject(Journal.class);                                    journal.setJournalId(snapshot.getId());//For updating we need a document reference                                    journalList.add(journal);                                }                                journalList.sort(new JournalSorter());                                Collections.reverse(journalList);                                journalRecyclerAdapter=new JournalRecyclerAdapter(ctx,journalList);                                recyclerView.setAdapter(journalRecyclerAdapter);                                journalRecyclerAdapter.notifyDataSetChanged();                            }                            else{//                                Log.d(TAG,"User Data Empty");                            }                        }                    });    }

Error Message after user signs out and crash:

java.lang.NullPointerException: Attempt to invoke virtual method 'boolean com.google.firebase.firestore.QuerySnapshot.isEmpty()' on a null object reference        at com.name.myjournal.JournalListActivity$3.onEvent(JournalListActivity.java:187)        at com.name.myjournal.JournalListActivity$3.onEvent(JournalListActivity.java:182)        at com.google.firebase.firestore.Query.lambda$addSnapshotListenerInternal$2(Query.java:1038)        at com.google.firebase.firestore.Query$$Lambda$3.onEvent(Unknown Source:6)        at com.google.firebase.firestore.core.AsyncEventListener.lambda$onEvent$0(AsyncEventListener.java:42)        at com.google.firebase.firestore.core.AsyncEventListener$$Lambda$1.run(Unknown Source:6)        at android.os.Handler.handleCallback(Handler.java:907)        at android.os.Handler.dispatchMessage(Handler.java:105)        at android.os.Looper.loop(Looper.java:216)        at android.app.ActivityThread.main(ActivityThread.java:7625)        at java.lang.reflect.Method.invoke(Native Method)        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:524)        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:987)W/Firestore: (21.5.0) [Firestore]: Listen for Query(target=Query(Journal where userId == # com.google.firestore.v1.Value@4376bde5    integer_value: 0    string_value: "YXiu3zAEH7Qirmn3FCgjRhhxMbk1" order by __name__);limitType=LIMIT_TO_FIRST) failed: Status{code=PERMISSION_DENIED, description=Missing or insufficient permissions., cause=null}I/Process: Sending signal. PID: 15971 SIG: 9

My firebase security rules Android Studio:.`

    service cloud.firestore {  match /databases/{database}/documents {  match /Journal/{JournalId}{       allow read:if request.auth!=null &&request.auth.uid==resource.data.userId;    allow create:if isAuthenticated() &&request.auth.uid==request.resource.data.userId;    allow update,delete:if isAuthenticated() &&request.auth.uid==resource.data.userId;   }    match /Users/{userId} {       allow read,write:if request.auth!=null;   }     function isAuthenticated(){       return request.auth!=null;   }  }}