[FIX] account: Instantiate potentially empty variable

If `journal_data` does not have a 'code' key, then the `journal`
variable never gets assigned and any references to it throw an
"UnboundLocalError: local variable 'journal' referenced before assignment"

We avoid this by assigning to journal an initial value of None.

closes odoo/odoo#129542

X-original-commit: b9cbb96c1ded18deb344cbf578083e6a0e9a353e
Signed-off-by: Florian Gilbert (flg) <flg@odoo.com>

addons/account/models/chart_template.py

@@ -226,6 +226,7 @@ class AccountChartTemplate(models.AbstractModel):
             if self.ref(xmlid, raise_if_not_found=False):
                 del data['account.journal'][xmlid]
             else:
+                journal = None
                 if 'code' in journal_data:
                     journal = self.env['account.journal'].with_context(active_test=False).search([
                         *self.env['account.journal']._check_company_domain(company),