No access possible via a 'NULL' data reference. Error message on Item-Event-AfterModify.absl

Hello,

May I ask your assistance because there is an error "No access possible via a 'NULL' data reference" on our script

SalesOrder-Item-Event-AfterModify.absl

NodeID of "this" was: 00163EAB9E511EEBB0ED9FC627C65FCC

Script below is

if (this.ItemProduct.IsSet())

{

if (!this.ItemProduct.QuantityMeasureUnitCode.IsInitial())

{

this.ItemProduct.QuantityMeasureUnitCode = quantitycoversion.CorrespondingQuantity.unitCode;

}

}

Thank you.