File, Import Information; Unhandled exception when importing Clients with no Client Group defined

If a Client Group is not defined as a default on User Preferences and the Client Group is not defined in the import XML then importing Clients will error when creating the next Auto Sequence Id.

The following error would occur:
Unhandled exception; Cannot access user interface when in a transaction.

There is now validation when saving the Client to ensure a Client Group has been assigned to the Client.