Missing province name reported as an error.

Massa,

Steps:

1. Click on "Add Address" (or create a new user)

2. Select a country with provinces, but do not enter anything in the province field

3. Click on Save

You get an error saying that the "" province is no good for that country.

The patch let go if the province is not defined. If it is required, the normal Drupal form will catch the error anyway.

Also, I optimized by computing the field name only if an error occurs.

Thank you.
Alexis