Application crash

The application crashes if it is opened from a minimized state. And the fall does not happen every time. I caught this log:

Fatal Exception: java.lang.RuntimeException: Unable to resume activity {biz.zismo.m/biz.zismo.m.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.webkit.WebView.onResume()' on a null object reference at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2963) at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:2994) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2373) at android.app.ActivityThread.access$800(ActivityThread.java:144) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1285) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:135) at android.app.ActivityThread.main(ActivityThread.java:5235) at java.lang.reflect.Method.invoke(Method.java) at java.lang.reflect.Method.invoke(Method.java:372) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:898) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:693) Caused by java.lang.NullPointerException: Attempt to invoke virtual method 'void android.webkit.WebView.onResume()' on a null object reference at biz.zismo.m.providers.web.WebviewFragment.onResume(WebviewFragment.java:337) at android.support.v4.app.Fragment.performResume(Fragment.java:2120) at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1147) at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1286) at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1268) at android.support.v4.app.FragmentManagerImpl.dispatchResume(FragmentManager.java:2153) at android.support.v4.app.FragmentController.dispatchResume(FragmentController.java:223) at android.support.v4.app.FragmentActivity.onResumeFragments(FragmentActivity.java:522) at android.support.v4.app.FragmentActivity.onPostResume(FragmentActivity.java:511) at android.support.v7.app.AppCompatActivity.onPostResume(AppCompatActivity.java:178) at android.app.Activity.performResume(Activity.java:6100) at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2952) at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:2994) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2373) at android.app.ActivityThread.access$800(ActivityThread.java:144) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1285) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:135) at android.app.ActivityThread.main(ActivityThread.java:5235) at java.lang.reflect.Method.invoke(Method.java) at java.lang.reflect.Method.invoke(Method.java:372) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:898) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:693) 

MainActivity:

 public class MainActivity extends AppCompatActivity implements NavDrawerCallback { private Toolbar mToolbar; private NavDrawerFragment mNavigationDrawerFragment; //Data to pass to a fragment public static String FRAGMENT_DATA = "transaction_data"; public static String FRAGMENT_CLASS = "transation_target"; public static boolean TABLET_LAYOUT = true; //Permissions Queu NavItem queueItem; SharedPreferences prefs; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); Fabric.with(this, new Crashlytics()); if (useTabletMenu()){ setContentView(R.layout.activity_main_tablet); Helper.setStatusBarColor(MainActivity.this, ContextCompat.getColor(this, R.color.myPrimaryDarkColor)); } else if (Config.USE_NEW_DRAWER == true) { setContentView(R.layout.activity_main_alternate); } else { setContentView(R.layout.activity_main); Helper.setStatusBarColor(MainActivity.this, ContextCompat.getColor(this, R.color.myPrimaryDarkColor)); } mToolbar = (Toolbar) findViewById(R.id.toolbar_actionbar); setSupportActionBar(mToolbar); if (!useTabletMenu()) getSupportActionBar().setDisplayShowHomeEnabled(true); else { getSupportActionBar().setDisplayShowHomeEnabled(false); } mNavigationDrawerFragment = (NavDrawerFragment) getSupportFragmentManager() .findFragmentById(R.id.fragment_drawer); if (Config.USE_NEW_DRAWER == true && !useTabletMenu()) { mNavigationDrawerFragment.setup(R.id.scrimInsetsFrameLayout, (DrawerLayout) findViewById(R.id.drawer), mToolbar); mNavigationDrawerFragment .getDrawerLayout() .setStatusBarBackgroundColor( ContextCompat.getColor(this, R.color.myPrimaryDarkColor)); findViewById(R.id.scrimInsetsFrameLayout).getLayoutParams().width = getDrawerWidth(); } else { mNavigationDrawerFragment.setup(R.id.fragment_drawer, (DrawerLayout) findViewById(R.id.drawer), mToolbar); DrawerLayout.LayoutParams params = (android.support.v4.widget.DrawerLayout.LayoutParams) mNavigationDrawerFragment.getView().getLayoutParams(); params.width = getDrawerWidth(); mNavigationDrawerFragment.getView().setLayoutParams(params); } if (useTabletMenu()) { mNavigationDrawerFragment .getDrawerLayout().setDrawerLockMode(DrawerLayout.LOCK_MODE_LOCKED_OPEN); mNavigationDrawerFragment .getDrawerLayout().setScrimColor(Color.TRANSPARENT); } else { mNavigationDrawerFragment .getDrawerLayout().setDrawerLockMode(DrawerLayout.LOCK_MODE_UNLOCKED); } Helper.admobLoader(this, getResources(), findViewById(R.id.adView)); prefs = PreferenceManager.getDefaultSharedPreferences(getBaseContext()); Helper.updateAndroidSecurityProvider(this); // setting push enabled String push = getString(R.string.rss_push_url); if (null != push && !push.equals("")) { // Create object of SharedPreferences. boolean firstStart = prefs.getBoolean("firstStart", true); if (firstStart) { final ServiceStarter alarm = new ServiceStarter(); SharedPreferences.Editor editor = prefs.edit(); alarm.setAlarm(this); // now, just to be sure, where going to set a value to check if // notifications is really enabled editor.putBoolean("firstStart", false); // commits your edits editor.commit(); } } // Check if we should open a fragment based on the arguments we have boolean loadedFragment = false; if (getIntent().getExtras() != null && getIntent().getExtras().containsKey(FRAGMENT_CLASS)) { try { Class<? extends Fragment> fragmentClass = (Class<? extends Fragment>) getIntent().getExtras().getSerializable(FRAGMENT_CLASS); if (fragmentClass != null) { String[] extra = getIntent().getExtras().getStringArray(FRAGMENT_DATA); Fragment fragment = fragmentClass.newInstance(); showFragment(fragment, extra, getTitle().toString()); loadedFragment = true; } } catch (Exception e) { //If we come across any errors, just continue and open the default fragment Log.printStackTrace(e); } } //If we haven't already loaded an item (or came from rotation and there was already an item) //Load the first item if (savedInstanceState == null && !loadedFragment){ mNavigationDrawerFragment.loadInitialItem(); } // Checking if the user would prefer to show the menu on start boolean checkBox = prefs.getBoolean("menuOpenOnStart", false); if (checkBox == true && !useTabletMenu()) { mNavigationDrawerFragment.openDrawer(); } } @Override public boolean onCreateOptionsMenu(Menu menu) { // getMenuInflater().inflate(R.menu.rss_menu, menu); return super.onCreateOptionsMenu(menu); } @SuppressLint("NewApi") @Override public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) { switch (requestCode) { case 1: boolean foundfalse = false; for (int i = 0; i < grantResults.length; i++) { if (grantResults[i] != PackageManager.PERMISSION_GRANTED) { foundfalse = true; } } if (!foundfalse){ openNavigationItem(queueItem); } else { // Permission Denied Toast.makeText(MainActivity.this, getResources().getString(R.string.permissions_required), Toast.LENGTH_SHORT) .show(); } break; default: super.onRequestPermissionsResult(requestCode, permissions, grantResults); } } //Perform the opening of a (selected) navItem private void openNavigationItem(NavItem item){ try { Fragment fragment = item.getFragment().newInstance(); if (fragment != null) { //Verify if we can safely open the fragment by checking for permissions if (checkPermissionsHandleIfNeeded(item, fragment) && checkPurchaseHandleIfNeeded(item)){ String[] extra = item.getData(); if (fragment instanceof CustomIntent) { CustomIntent.performIntent(MainActivity.this, extra); } else { showFragment(fragment, extra, item.getText(this)); } } else { //We do nothing, the check method will handle this for us. } } else { Log.v("INFO", "Error creating fragment"); } } catch (InstantiationException e) { Log.printStackTrace(e); } catch (IllegalAccessException e) { Log.printStackTrace(e); } } //Show a fragment in the MainActivity's fragment viewer public void showFragment(Fragment fragment, String[] extra, String title){ Bundle bundle = new Bundle(); bundle.putStringArray(FRAGMENT_DATA, extra); fragment.setArguments(bundle); FragmentManager fragmentManager = getSupportFragmentManager(); fragmentManager.beginTransaction() .replace(R.id.container, fragment).commitAllowingStateLoss(); if(!useTabletMenu()) setTitle(title); } @SuppressLint("NewApi") @Override public void onNavigationDrawerItemSelected(int position, NavItem item) { openNavigationItem(item); } /** * If the item can be opened because it either has been purchased or does not require a purchase to show. * @param item Item to check * @return true if the item is safe to be opened. False if the item is not safe to open, simply don't open as we will handle. */ private boolean checkPurchaseHandleIfNeeded(NavItem item){ String license = getResources().getString(R.string.google_play_license); // if item does not require purchase, or app has purchased, or license is null/empty (app has no in app purchases) if (item.requiresPurchase() == true && !SettingsFragment.getIsPurchased(this) && null != license && !license.equals("")) { Fragment fragment = new SettingsFragment(); String[] extra = new String[] {SettingsFragment.SHOW_DIALOG}; showFragment(fragment, extra, item.getText(this)); return false; } return true; } /** * Checks if the item can be opened because it has sufficient permissions. * @param item The item to check * @param fragment The fragment instance associated to this item. * @return true if the item is safe to open */ private boolean checkPermissionsHandleIfNeeded(NavItem item, Fragment fragment){ if (fragment instanceof PermissionsFragment && android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.M) { String[] permissions = ((PermissionsFragment) fragment).requiredPermissions(); boolean allGranted = true; for (String permission : permissions) { if (checkSelfPermission(permission) != PackageManager.PERMISSION_GRANTED) allGranted = false; } if (!allGranted) { //TODO An explaination before asking requestPermissions(permissions, 1); queueItem = item; return false; } return true; } return true; } @Override public void onBackPressed() { Fragment activeFragment = getSupportFragmentManager().findFragmentById( R.id.container); if (mNavigationDrawerFragment.isDrawerOpen()) { mNavigationDrawerFragment.closeDrawer(); } else if (activeFragment instanceof BackPressFragment){ boolean handled = ((BackPressFragment) activeFragment).handleBackPress(); if (!handled){ super.onBackPressed(); } } else { super.onBackPressed(); } } @Override protected void onActivityResult(int requestCode, int resultCode, Intent data) { super.onActivityResult(requestCode, resultCode, data); List<Fragment> fragments = getSupportFragmentManager().getFragments(); if (fragments != null) for (Fragment frag : fragments) if (frag != null) frag.onActivityResult(requestCode, resultCode, data); } //Get the width of the drawer private int getDrawerWidth(){ // Navigation Drawer layout width int width = getResources().getDisplayMetrics().widthPixels; TypedValue tv = new TypedValue(); int actionBarHeight; if (getTheme().resolveAttribute(android.R.attr.actionBarSize, tv, true)) { actionBarHeight = TypedValue.complexToDimensionPixelSize(tv.data,getResources().getDisplayMetrics()); } else { actionBarHeight = 0; } int possibleMinDrawerWidth = width - actionBarHeight; int maxDrawerWidth = getResources().getDimensionPixelSize(R.dimen.drawer_width); return Math.min(possibleMinDrawerWidth, maxDrawerWidth); } //Check if we should adjust our layouts for tablets public boolean useTabletMenu(){ return (getResources().getBoolean(R.bool.isWideTablet) && TABLET_LAYOUT); } }