[FIX] web: adding toggle to view with studio

Steps to reproduce:
- edit RFQ model with studio
- add a toggle widget to the product list
- activate/deactivate the toggle multiple times on different products

Bug:
sometimes the element on the widget is undefined when trying to rerender

Fix:
check the element is defined before trying to render it

opw-3013024

closes odoo/odoo#103186

Signed-off-by: Aaron Bohy (aab) <aab@odoo.com>