Android Studio: Unable to instantiate activity ComponentInfo

I am trying to open a new Activity in Android Studio on a Button Press.

public class Home extends AppCompatActivity {

    private Button button;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_home);

        button = findViewById(R.id.btnAddSubject);
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                addSubject();
            }
        });
    }
    public void addSubject(){
        Intent intent = new Intent(this, AddSubject.class);
        startActivity(intent);
    }
}

I get the following error:

java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.smarkmarks/com.example.smarkmarks.AddSubject}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.res.Resources android.content.Context.getResources()' on a null object reference

Read more here: https://stackoverflow.com/questions/66274416/android-studio-unable-to-instantiate-activity-componentinfo