Small improvement

app/src/main/java/eu/faircode/email/FragmentMessages.java

@@ -1950,6 +1950,7 @@ public class FragmentMessages extends FragmentBase implements SharedPreferences.
                             @Override
                             public void run() {
                                 try {
+                                    if (adapter != null)
                                         adapter.notifyItemChanged(pos);
                                 } catch (Throwable ex) {
                                     Log.e(ex);