using 1.4.7
In setup.pl menu "add user"/"enter user" menu. If employee# empty then perl error is thrown either set number based on some pre-defined value or validate field before submitting form.
If the error occurs then the web from is cleared. Re-entering user in webform results in error as the user now does exist. So there is also no way to correct the error.
https://github.com/ledgersmb/LedgerSMB/pull/548