Fix view model crashes when long-running task finishes after model is cleared (#1259)

Author: SUPERCILEX

auth/src/main/java/com/firebase/ui/auth/viewmodel/ViewModelBase.java

@@ -39,6 +39,5 @@ protected void setArguments(T arguments) {
     @Override
     protected void onCleared() {
         mIsInitialized.set(false);
-        mArguments = null;
     }
 }