Repro steps: 

1.  Synch RH content and register a system to katello.  Associate system with
RH repo.
2.  Navigate to systems and click on the system you registered.
3.  Click on the errata subtab in the system view
4.  Assure no errata are selected; click the "Run" button.

Current results:
undefined method `errors' for #

Expected results:
* Run button does nothing, or
* Run button tells user they need to select errata first, or
* Run button should be disabled if no errata selected.