Before this commit, when we have a list (editable top) in a form
with some mandatory fields and some existing rows. If we click on
'add a line', a new empty line appear on the top, then we click on
the last row, the empty row will disappear and we will have a
traceback.
After this commit, if we repeat this scenario, we click on the last
row, we will be able to edit this last row.
closesodoo/odoo#38471
X-original-commit: 996f77b03eaf6dd646b1816e7f70209d5ee6f8df
Signed-off-by: jbm-odoo <jbm-odoo@users.noreply.github.com>