External Parties Add-On; Deleting an Employee of an External Party may give contraint message

When trying to delete an External Party Employee that is an External User (Users & Responsibilities form, External page), the following message is displayed:

ERROR MESSAGE
=============
Failed to save External Party.
Failed to save Client.
Failed to save Client Employments.
Failed to delete one or more records from table 'ClientEmployment'.
Failed to execute SQL.
The DELETE statement conflicted with the REFERENCE constraint "RI_ClientEmploymentUser_1". The conflict occurred in database "finPOWERConnect", table "dbo.User", column 'ExternalPartyEmployeePk'.
The statement has been terminated.

The above message is from a SQL Server database, Access message is similar.

This will now give a user friendly message:

ERROR MESSAGE
===============
Failed to save External Party.
Failed to save Client.
Failed to save Client Employments.
One or more Users are using an Employee you have deleted.