[UWS] Cancel last commit. The UWSException was thrown intentionnaly: if an error occurs while just creating the thread, this error should not impact the job ; it is an internal server error, not an error due to the job execution or of a wrong parameter. This error MUST be thrown AND the job MUST stay PENDING (so that it can be restarted later when the server bug will be fixed). Job parameters checks MUST be done either in the job execution (JobThread.jobWork()) or at the job creation (using an InputParamController).