Fixed crash when validations fail while creating a catalog item

```create_request``` returns ```false``` if validations fail or it returns the ```request``` object itself.
An additional check was added to check for the existence of the ```request``` object.

https://bugzilla.redhat.com/show_bug.cgi?id=1095457
https://bugzilla.redhat.com/show_bug.cgi?id=1138397