2019-04-03 13:43:21.850 10927-10927/com.example.smarthub E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.smarthub, PID: 10927
    java.lang.NullPointerException: Attempt to invoke virtual method 'com.google.android.gms.tasks.Task com.google.firebase.auth.FirebaseAuth.createUserWithEmailAndPassword(java.lang.String, java.lang.String)' on a null object reference
        at com.example.smarthub.RegisterActivity.DangKy(RegisterActivity.java:59)
        at com.example.smarthub.RegisterActivity.access$000(RegisterActivity.java:16)
        at com.example.smarthub.RegisterActivity$1.onClick(RegisterActivity.java:42)
        at android.view.View.performClick(View.java:6597)
        at android.view.View.performClickInternal(View.java:6574)
        at android.view.View.access$3100(View.java:778)
        at android.view.View$PerformClick.run(View.java:25885)
        at android.os.Handler.handleCallback(Handler.java:873)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:193)
        at android.app.ActivityThread.main(ActivityThread.java:6669)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)