[TYPO3-commerce] No warning when buyproces halts because of email previously used

[Stephan Viftrup]

Hi there

I discovered that when previous buyer returns and tries to buy a 
product he can not enter his emailadress again (unless he is logged in 
perhaps).  The process will halt when submitting the adress but no 
error is shown.

I wonder if it is something mission in the template (for testing i am 
using the default template) or if it is an error or shortcoming in the 
script?

Good practice might be to offer the returning buyer a change to enter 
the coresponding password without interferring with the checkout 
process.

thank you for your time

Stephan