From ff61cdc68a4eb3763d9f7181a1a5a7de0982976f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?C=C3=A9dric=20Krier?= <ced@b2ck.com>
Date: Sun, 6 Mar 2022 13:43:50 +0100
Subject: [PATCH] Do not fail on missing attribute in InvoiceTax._key

issue11136
review370911002
(grafted from ac674a252a05d63c3ee61a277d7abeb394edc10f)

--HG--
branch : 6.0
---
 invoice.py | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/invoice.py b/invoice.py
index 538f9ee9b8..71e98a6216 100644
--- a/invoice.py
+++ b/invoice.py
@@ -2587,8 +2587,10 @@ class InvoiceTax(sequence_ordered(), ModelSQL, ModelView):
     @property
     def _key(self):
         # Same as _TaxKey
-        tax_id = self.tax.id if self.tax else -1
-        return (self.account.id, tax_id, self.base >= 0)
+        tax_id = self.tax.id if getattr(self, 'tax', None) else -1
+        account_id = (
+            self.account.id if getattr(self, 'account', None) else None)
+        return (account_id, tax_id, (getattr(self, 'base', 0) or 0) >= 0)
 
     @classmethod
     def check_modify(cls, taxes):