"FATAL EXCEPTION: main
                                                                       java.lang.NullPointerException
                                                                           at com.example.ghost.prochat.MainActivity$1.onComplete(MainActivity.java:134)"

FirebaseAuth.getInstance().createUserWithEmailAndPassword(email, password) .addOnCompleteListener(this, new OnCompleteListener<AuthResult>() {
        @Override
        public void onComplete(@NonNull Task<AuthResult> task) {
            Logger.getLogger(LoginActivity.class.getName()).log(Level.ALL, "createUserWithEmailAndPassword:onComplete:" + task.isSuccessful());
            registerProgressDlg.dismiss();
            if (!task.isSuccessful()) {
                Logger.getLogger(MainActivity.class.getName()).log(Level.ALL, "createUserWithEmailAndPassword", task.getException());
                Utils.showDialog(
                        MainActivity.this,
                        getString(R.string.err_singup));
            }
            else {
                final ArrayList<String> defaultRoom = new ArrayList<String>();
                defaultRoom.add("home");
                // Update the user profile information
                final FirebaseUser user = task.getResult().getUser();
                UserProfileChangeRequest profileUpdates = new UserProfileChangeRequest.Builder()
                        .setDisplayName(String.valueOf(displayUsername))
                        .setPhotoUri(Uri.parse("https://example.com/jane-q-user/profile.jpg"))
                        .build();
                user.updateProfile(profileUpdates).addOnCompleteListener(new OnCompleteListener<Void>() {
                    @Override
                    public void onComplete(@NonNull Task<Void> task) {
                        if (task.isSuccessful()) {
                            Logger.getLogger(MainActivity.class.getName()).log(Level.ALL, "User profile updated.");
                            // Construct the ChatUser
                            UserList.user = new ChatUser(user.getUid(),displayUsername, editTextEmail,true,defaultRoom);
                            // Setup link to users database
                            FirebaseDatabase.getInstance().getReference("users").child(user.getUid()).setValue(UserList.user);
                            startActivity(new Intent(MainActivity.this, UserList.class));
                            finish();
                        }
                    }
                });
            }
        }
    });
}