slapos_cloud: return nothing is no Software Product is found

master/bt5/slapos_cloud/SkinTemplateItem/portal_skins/slapos_cloud/InstanceTree_getSoftwareProduct.py

@@ -4,20 +4,22 @@ software_product = None
 software_release = None
 software_type = None
 
+use_category_uid = portal.restrictedTraverse("portal_categories/use/trade/sale").getUid(),
 product_list = portal.portal_catalog(
   portal_type="Software Product",
   validation_state=['validated', 'published'],
-  use__relative_url="trade/sale",
+  use__uid=use_category_uid,
   follow_up__uid=context.getFollowUpUid()
 )
 
-software_release = portal.portal_catalog.getResultValue(
+if len(product_list) != 0:
+  software_release = portal.portal_catalog.getResultValue(
     portal_type="Software Product Release Variation",
     url_string=url_string,
     parent_uid=[x.getUid() for x in product_list]
-)
+  )
 
-if software_release is not None:
+  if software_release is not None:
     software_product = software_release.getParentValue()
 
     software_type = portal.portal_catalog.getResultValue(