Prevent crash

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

@@ -3018,6 +3018,9 @@ public class FragmentMessages extends FragmentBase implements SharedPreferences.
         model.getIds(getContext(), getViewLifecycleOwner(), new Observer<List<Long>>() {
             @Override
             public void onChanged(List<Long> ids) {
+                new Handler().post(new Runnable() {
+                    @Override
+                    public void run() {
                         selectionTracker.clearSelection();
                         for (long id : ids)
                             selectionTracker.select(id);
@@ -3029,6 +3032,8 @@ public class FragmentMessages extends FragmentBase implements SharedPreferences.
                     }
                 });
             }
+        });
+    }
 
     private void onMenuEmpty(String type) {
         Bundle aargs = new Bundle();