Create records from custom module to custom module with subform on both module by using function

Hi,

I had created two custom module, and created a function to be trigger when condition meet.

The function will copy the records from module A to module B , along with subform details.

However, I had encounter error:
Failed to execute function Mismatch of data type expression. Expected List but found String Line Number:14

Please find details and script as below:

Custom Module A: Robot_RMA

Subform name : Subform_2

Lookup Field : SN_ID, Customer, Replacement_SN_ID

Single Line Field : Name, FSR_No

Lookup Field on subform : Component_SN_ID, Replace_Comp_SN_ID

Custom Module B: Robot3

Subform name : Component_History

Lookup Field : SN, Customer, RMA, Replacement_SN_ID

Single Line Field : FSR_No

Lookup Field on subform : Defect_Comp_ID, Swap_Comp_ID

rmaInfo = zoho.crm.getRecordById("Robot_RMA",rmaId.toLong());

//info rmaInfo;

mp = Map();

mp.put("SN",ifnull(rmaInfo.get("SN_ID"),""));

mp.put("Customer",ifnull(rmaInfo.get("Customer"),""));

mp.put("RMA",ifnull(rmaInfo.get("Name"),""));

mp.put("Replacement_SN_ID",ifnull(rmaInfo.get("Replacement_SN_ID"),""));

mp.put("FSR",ifnull(rmaInfo.get("FSR_No"),""));

sub_forms = List();

//info subinfo;

subinfo = ifnull(rmaInfo.get("Subform_2"),"");

for each rec in subinfo

{

componentDefectSN = ifnull(rec.get("Component_SN_ID"),"").get("id");

if(componentDefectSN != "")

{

subform = Map();

subform.put("Defect_Comp_ID",rec.get("Component_SN_ID").get("id"));

subform.put("Swap_Comp_ID",rec.get("Replace_Comp_SN_ID").get("id"));

sub_forms.add(subform);

//info sub_forms;

}

mp.put("Subform_2",sub_forms);

create = zoho.crm.createRecord("Robot3",mp);

info create;