NullPointerException and NumberFormatException

app/src/main/java/de/sebse/fuplanner/MainActivity.java

@@ -500,6 +500,7 @@ public class MainActivity extends AppCompatActivity
             case FRAGMENT_CANTEENS_DETAILS:
                 getCanteenBrowser().getCanteens(success -> {
                     int size = mNavigationView.getMenu().size();
+                    try {
                         Canteen canteen = success.getCanteen(Integer.parseInt(mFragmentData));
                         //noinspection ConstantConditions
                         String title = canteen == null ? null : canteen.getName();
@@ -510,6 +511,9 @@ public class MainActivity extends AppCompatActivity
                                 break;
                             }
                         }
+                    } catch (NumberFormatException e) {
+                        e.printStackTrace();
+                    }
                 }, log::e);
                 return;
             case FRAGMENT_CANTEENS:

app/src/main/java/de/sebse/fuplanner/fragments/PrefsFragment.java

@@ -53,6 +53,7 @@ public class PrefsFragment extends PreferenceFragmentCompat implements SharedPre
 
         if (getActivity() != null && getActivity() instanceof MainActivity) {
             CustomAccountManager accountManager = ((MainActivity) getActivity()).getAccountManager();
+            if (accountManager != null) {
                 Account accountByType = accountManager.getAccountByType(AccountGeneral.ACCOUNT_TYPE);
                 if (accountByType != null) {
                     ContentResolver.setSyncAutomatically(accountByType, KVVContentProvider.PROVIDER_NAME, true);
@@ -64,4 +65,5 @@ public class PrefsFragment extends PreferenceFragmentCompat implements SharedPre
                 }
             }
         }
+    }
 }