erp5_core: 0 if null to not break calculate

product/ERP5/bootstrap/erp5_core/SkinTemplateItem/portal_skins/erp5_core/Resource_zGetAssetPrice.sql

@@ -24,7 +24,7 @@ from
         select
             month(date) as d_month,
             year(date) as d_year,
-            SUM(IF(quantity>0, total_price, 0)) as incoming_total_price,
+            SUM(IF(quantity>0, IFNULL(total_price, 0), 0)) as incoming_total_price,
             SUM(IF(quantity>0, quantity, 0)) as incoming_total_quantity,
             SUM(IF(quantity>0, 0, quantity)) as outgoing_total_quantity,
             SUM(quantity) as quantity_diff