erp5_project: return empty if not related task/report

bt5/erp5_project/SkinTemplateItem/portal_skins/erp5_project/Project_getSourceProjectRelatedTaskReportList.py

@@ -36,6 +36,8 @@ task_list.extend([x.getObject() for x in \
                          source_project_uid = source_project_uid_list,
                          simulation_state = task_report_simulation_state,
                          **sql_kw)])
+if len(task_list) == 0:
+  return []
 
 key_value = kw.pop('source_title', None)
 if key_value: