TypeError in Google Sheets Script "Cannot read property '0' of undefined

Question

I am trying to create a script that writes to one sheet based on values set in another sheet. The script runs when an update button is clicked. The script runs well and I get the desired outcome but once it has completed the task it then errors out with the above error. Not sure where I am going wrong.

function UPDATE(){
  
  var ss = SpreadsheetApp.getActiveSpreadsheet(); //Get the Spreadsheet
  var s = ss.getActiveSheet(); //Get the Sheet
  Logger.log('Script started');//Log Script Start
  //Prepare a datestamp
  var timeZone = Session.getScriptTimeZone();
  date = Utilities.formatDate(new Date(), timeZone, "dd/MM/yyyy HH:mm:ss");

  //Check Active Sheet is correct
  if( s.getName() == "ABA"){
    
    var sheet2 = ss.getSheetByName('Filtering');//Get the Data Sheet
    var data = s.getDataRange().getValues(); //Get Active Sheet Data Values
    var data2 = sheet2.getDataRange().getValues(); //Get Data Sheet Data Values
        //Run through Active Sheet Data Values
        for(var i = 0; i<data[0].length; i++){
          //Check if Required Column has been altered
          if(data[i][12] > 0){ 
            var the_id = s.getRange(i+1,2).getValue(); // Set ID of altered Row
            var assignee = s.getRange(i+1, 13).getValue(); // Get Value of altered column
            
            //Find corresponding ID in Data Sheet Data Values 
            for(var j = 0; i<data2[0].length-1; j++){
              //Check is row contains ID
              if(data2[j][0] == the_id){
                sheet2.getRange(j+1, 21).setValue(assignee); //WRITE to Data Sheet
                sheet2.getRange(j+1, 23).setValue(date); //WRITE to Data Sheet
                s.getRange(i+1, 12).setValue(""); //Blank Altered Row value
              }
            }
          }
        }
    s.getRange(2, 4).setValue("Updated @ "+date);//WRITE to Active Sheet to Show Update completed

  }
}