pickup: try to print string formatted ApiError on error

Related: SYS#5452

models/shipcloud_pickup.py

@@ -69,10 +69,10 @@ class SCPickup(models.Model):
         try:
             result = api.create_pickup(sc_pickup)
         except shipcloud.ApiError as err:
-            raise Warning(err)
+            raise Warning(str(err))
         _logger.info("shipcloud response: %s", result)
         self.sc_pickup_id = result['id']
-        self.sc_pickup_id = result['carrier_pickup_number']
+        self.carrier_pickup_number = result['carrier_pickup_number']
         self.state = 'confirmed'
 
     # somehow this didn't work as a new (v8) style ORM ?!?