erp5_workflow: rename chain_by_type repair script; add a type check in convertion workflow.

bt5/erp5_workflow/SkinTemplateItem/portal_skins/erp5_workflow/WorkflowTool_convertWorkflow.xml

@@ -89,10 +89,10 @@ for dc_wf in selected_wf_list:\n
 \n
   type_workflow_dict = context.getChainsByType()\n
   for ptype_id in type_workflow_dict:\n
-    ptype = getattr(context.getPortalObject().portal_types, ptype_id)\n
+    ptype = getattr(context.getPortalObject().portal_types, ptype_id, None)\n
+    if ptype is not None:\n
       # 1. clean DC workflow assignement:\n
       context.delTypeCBT(ptype.id, dc_wf.id)\n
-\n
       # 2. assign ERP5 Workflow to portal type:\n
       type_workflow_list = ptype.getTypeWorkflowList()\n
       if workflow.getId() not in type_workflow_list:\n