Fix NPE in GtasksDetailExposer

astrid/src/main/java/com/todoroo/astrid/gtasks/GtasksDetailExposer.java

@@ -77,7 +77,7 @@ public class GtasksDetailExposer extends BroadcastReceiver {
             return null;
         }
         String listName = gtasksListService.getListName(listId);
-        if(listName.equals(GtasksListService.LIST_NOT_FOUND)) {
+        if(listName == null) {
             return null;
         }