NullPointerException с фрагменти

Приложението ми съдържа ViewPager в MainActivity с два фрагмента. Първият фрагмент съдържа ListView. Никога не виждам това, но виждам отчети от потребители за RuntimeException в Google Play:

java.lang.RuntimeException: Unable to resume activity {com.my.project/com.my.project.MainActivity}: java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=1, result=-1, data=Intent { (has extras) }} to activity {com.my.project/com.my.project.MainActivity}: java.lang.NullPointerException
 at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2120)
 at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:2135)
 at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1668)
 at android.app.ActivityThread.access$1500(ActivityThread.java:117)
 at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
 at android.os.Handler.dispatchMessage(Handler.java:99)
 at android.os.Looper.loop(Looper.java:130)
 at android.app.ActivityThread.main(ActivityThread.java:3683)
 at java.lang.reflect.Method.invokeNative(Native Method)
 at java.lang.reflect.Method.invoke(Method.java:507)
 at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:875)
 at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:633)
 at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=1, result=-1, data=Intent { (has extras) }} to activity {com.my.project/com.my.project.MainActivity}: java.lang.NullPointerException
 at android.app.ActivityThread.deliverResults(ActivityThread.java:2532)
 at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2107)
 ... 12 more
Caused by: java.lang.NullPointerException
 at com.my.project.FirstFragment.load(FirstFragment.java:551)
 at com.my.project.MainActivity.onActivityResult(MainActivity.java:132)
 at android.app.Activity.dispatchActivityResult(Activity.java:3908)
 at android.app.ActivityThread.deliverResults(ActivityThread.java:2528)
 ... 13 more

Ето код от FirstFragment.java:

public class FirstFragment extends Fragment {

    ArrayList<ListItemObject> listItems = null;
    ArrayAdapter<ListItemObject> mAdapter;

    void load() {
            mAdapter.clear(); // I get error here, that is FirstFragment.java:551
            ...
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        super.onCreateView(inflater, container, savedInstanceState);

        listItems = new ArrayList<ListItemObject>();
        mAdapter = new MyAdapter(getActivity(), listItems);
        listView.setAdapter(mAdapter);
    }

}

Това са всички случаи на mAdapter. И не мога да разбера как може да причини NullPointerException. Мисля, че понякога Fragment1 унищожава и пресъздава, но без onCreateView(). Разговарям с един от потребителите, които имат този проблем, и той ми каза, че този бъг изчезва, след като премахне отметката от „Не запазвай дейности“ в „Опции за разработчици“ в настройките. Не знам , мога ли да го поправя? Или трябва да кажа на всички мои потребители „премахнете отметката от тази опция“?

В моята NainActivity:

public class MainActivity extends FragmentActivity {

    Vector<Fragment> fragments;
    ViewPager viewPager;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        viewPager = (ViewPager) findViewById(R.id.pager);

        fragments = new Vector<Fragment>();
        fragments.add(Fragment.instantiate(this, Fragment1.class.getName()));
        fragments.add(Fragment.instantiate(this, Fragment2.class.getName()));

        viewPager.setOffscreenPageLimit(fragments.size());
        PagerAdapter pagerAdapter = new PagerAdapter(super.getSupportFragmentManager(), fragments);

        viewPager.setAdapter(pagerAdapter);

        viewPager.setCurrentItem(0);
    }

    @Override
    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        if(requestCode==1) {
            ((MainChat)fragments.get(0)).load();
        }
    }

    class PagerAdapter extends FragmentPagerAdapter implements IconPagerAdapter {

        private List<Fragment> fragments;

        public PagerAdapter(FragmentManager fm, List<Fragment> fragments) {
            super(fm);
            this.fragments = fragments;
        }

        @Override
        public Fragment getItem(int position) {
            return this.fragments.get(position);
        }

        @Override
        public int getCount() {
            return this.fragments.size();
        }

    }

}