[16.0][FIX] account_chart_update: Translatable fields without translations may raise errors as its fetched by the wizard but has no translated value

@moduon MT-8280

account_chart_update_multilang/wizards/wizard_chart_update.py

@@ -31,8 +31,11 @@ class WizardUpdateChartsAccount(models.TransientModel):
             for key in self._diff_translate_fields(template, rec):
                 for lang in self._other_langs():
                     field = rec._fields[key]
-                    old_value = field._get_stored_translations(rec).get(
-                        rec.env.lang, "en_US"
+                    stored_translation_rec = field._get_stored_translations(rec)
+                    if not stored_translation_rec:
+                        continue
+                    old_value = (
+                        stored_translation_rec.get(rec.env.lang or "en_US") or ""
                     )
                     if old_value.startswith("<p>") and old_value.endswith("</p>"):
                         old_value = old_value[3:-4]