Fixed loading saved search

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

@@ -1381,6 +1381,7 @@ public class BoundaryCallbackMessages extends PagedList.BoundaryCallback<TupleMe
 
         public static SearchCriteria fromJsonData(JSONObject json) throws JSONException {
             SearchCriteria criteria = new SearchCriteria();
+            if (!json.isNull("query"))
                 criteria.query = json.optString("query");
             criteria.fts = json.optBoolean("fts");
             criteria.in_senders = json.optBoolean("in_senders");