get rid of undef warning in QueryString element
get rid of undef wanring when we sanitiza arguments
adjust charts test

* structure of the table has been changed
* "Tickets" was changed to "Ticket count"
* default is group by status
* catch warnings
* mark one test as TODO, incorrect grouppings
  are skipped and code falls back to status, but UI
  doesn't indicate that chart is groupped by status