[FIX] portal: portal share default get
[FIX] portal: portal share default get

Before this commit, we used dict keys before they existed
And made the share button crash

After this commit, there is no crash

OPW 1943301

closes odoo/odoo#31427
ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo