Fixed a crash in DisposableTaskListFragment

astrid/src/com/todoroo/astrid/activity/DisposableTaskListFragment.java

@@ -14,6 +14,7 @@ public class DisposableTaskListFragment extends TaskListFragment {
         Activity activity = getActivity();
         if (activity instanceof TaskListActivity) {
             TaskListActivity tla = (TaskListActivity) activity;
+            if (tla.getFragmentLayout() == AstridActivity.LAYOUT_SINGLE)
                 tla.getFragmentPagerAdapter().remove(filter);
         }
         super.onDetach();