Remove error

move.py

@@ -4,14 +4,11 @@
 from trytond.pool import PoolMeta
 from trytond.config import config as config_
 
-__all__ = ['Move']
-
 DIGITS = config_.getint('product', 'price_decimal', default=4)
 DISCOUNT_DIGITS = config_.getint('product', 'discount_decimal', default=4)
 
 
-class Move:
-    __metaclass__ = PoolMeta
+class Move(metaclass=PoolMeta):
     __name__ = 'stock.move'
 
     @classmethod

purchase.py

@@ -3,6 +3,8 @@
 # the full copyright notices and license terms.
 from datetime import date
 from decimal import Decimal
+
+from trytond.exceptions import UserError
 from trytond.model import ModelView, fields
 from trytond.wizard import Wizard, StateTransition, StateView, Button
 from trytond.pool import PoolMeta, Pool
@@ -14,7 +16,7 @@ from trytond.transaction import Transaction
 STATES = {
     'invisible': Eval('type') != 'line',
     'required': Eval('type') == 'line',
-    }
+}
 DIGITS = config_.getint('product', 'price_decimal', default=4)
 DISCOUNT_DIGITS = 6
 
@@ -61,9 +63,6 @@ class PurchaseLine(metaclass=PoolMeta):
             cls.amount.on_change_with.add('gross_unit_price')
         if 'discount' not in cls.quantity.on_change:
             cls.quantity.on_change.add('discount')
-        cls._error_messages.update({
-            'purchase_without_warehouse': ('Missing warehouse in purchase'),
-        })
 
     @staticmethod
     def default_discount():
@@ -118,7 +117,7 @@ class PurchaseLine(metaclass=PoolMeta):
     def on_change_with_stock_quantity(self, name=None):
         res = 0
         if not self.purchase.warehouse:
-            self.raise_user_error('purchase_without_warehouse')
+            raise UserError('purchase_without_warehouse')
         location_id = self.purchase.warehouse.id
         if self.product:
             stock_context = {