[FIX] estate: fix edge-case in validation of a new offer's price

A new offer's price must be at least equal to the one of the best existing offer.
We use the "best_price" computed field on "estate.property" for this and we must
account for the case when it hasn't been initialized yet. In that case, use 0 as a fallback.

Author: robal-odoo

estate/models/estate_property_offer.py

@@ -39,7 +39,8 @@ def _inverse_deadline(self) -> None:
     def create(self, vals):
         for val in vals:
             estate_property = self.env["estate.property"].browse(val["property_id"])
-            if val["price"] < estate_property.best_price:
+            best_price = estate_property.best_price or 0.0
+            if val["price"] < best_price:
                 raise UserError(_("A new offer must match or exceed the price of the current best offer."))
             estate_property.state = "offer_received"
         return super().create(vals)