Invalid sublist operation error in line init function

Hi,

I want to disable the loaction field in lineinit function for the new records and for old records for all the lines. I am getting Invalid sublist operation error for the new line that is added while editing the old records. I am getting the same error when i create a new record.

Location field getting disabled for existing lines for old records. Please help. Here is the code below.

define(['N/error', 'N/currentRecord'],

    function (error, currentRecord) {

        function lineInit(context) {

            try {

                var currentRecord = context.currentRecord;

                // var sublistId = scriptContext.sublistId;                // if (sublistId !== 'item') return;                // In SuiteScript 2.0 Line count starts with index 0;                var selectedLine = currentRecord.getCurrentSublistIndex({