Added check for blank on name entry

Resolves issue #5747
Since cancel just returns a blank this checks for that and doesn't raise an error.
I'm tempted to change this to an isnull check in the first bit since that will allow for more explicit trapping of a cancel vs a blank that looks like a cancel, but the isnull it can't be used after the reject_bad_name is called. The reason for this is that is that reject_bad_name returns null if the name is rejected so it always generates no error message.