fix: import + no symbol if None

assetsetting.py

@@ -5,6 +5,7 @@
 
 
 from trytond.model import ModelSingleton, ModelView, ModelSQL, fields
+from trytond.pool import Pool
 
 
 class AssetSetting(ModelSingleton, ModelSQL, ModelView):

reconciliation.py

@@ -42,7 +42,7 @@ class Reconciliation(metaclass=PoolMeta):
                     digits=self.quantity_digits),
                 'end_quantity': Report.format_number(self.end_quantity or 0.0, None,
                     digits=self.quantity_digits),
-                'uom_symbol': self.quantity_uom.symbol,
+                'uom_symbol': getattr(self.quantity_uom, 'symbol', '-'),
                 }
         return recname