Field values not saved when form error is triggered

Hi,

Here is how to reproduce this:

1. Create a content type with at least one field with an shs widget
2. Try to add a node of this content type, selecting something in the shs field you created, but leaving the title of this content empty (to trigger a form error saying that the title field is required)
3. You will notice that the values of the shs field are still displayed. Try to save the content again (still leaving the "Title" field empty)
4. The form triggers an error saying that the title field is required, you should now see however that the shs field is empty.

I believe that the issue comes from the fact that after the first attempt to save the content, the javascript function updateFieldValue is never called (given that the field value doesn't change). Will keep looking and hopefully provide a patch for it...