Error with the GetTransactionData workflow

When I updated the workflow and added the If condition to test if there is any new transaction to process, I get the error:
{
“message”: “Assign: Cannot create an L-value from the given expression with property ‘set_Item’ because the target object is null.”,
“level”: “Error”,
“logType”: “Default”,
“timeStamp”: “11:46:13”,
“processVersion”: “1.0.0.0”,
“jobId”: “70b08ee0-9854-4416-9a57-1c72469546fc”,
“robotName”: “MyLilRobot”,
“machineId”: 59727,
“fileName”: “GetTransactionData”,
“logF_BusinessProcessName”: “Framework”
}
Currently not sure what I am doing wrong.

variable%20assignment

Start the Transaction number from 0.
And in IF condition, in_TransactionNumber < in_WorkItems.Count