[FIX] account: no recompute when currency_id is unset

When the currency_id is unset from the invoice and account moves are set,
by means of updating taxes or the line itself,
since there are no checks on the actual presence of a currency,
currency methods will invoked causing crashes.

Imposing the condition directly on top of the onchange solves the issue.
Since the currency_id is a required field for the invoice the
recomputation will be triggered again with the correct values.

opw-2192628

closes odoo/odoo#48458

X-original-commit: f795b1bc7b42bdcbd4bd9895616461d2702f1e41
Signed-off-by: Nicolas Martinelli (nim) <nim@odoo.com>

addons/account/models/account_move.py

@@ -348,6 +348,8 @@ class AccountMove(models.Model):
 
     @api.onchange('date', 'currency_id')
     def _onchange_currency(self):
+        if not self.currency_id:
+            return
         if self.is_invoice(include_receipts=True):
             company_currency = self.company_id.currency_id
             has_foreign_currency = self.currency_id and self.currency_id != company_currency