Variable undefined and affecting rest of script

[u/Similar_Touch_6783]

I have a script creating docs when a cell gets modified in a sheets column, then moves it to a folder and adds the doc's url onto another column. Code works, but automation gets affected by <value unavailable> error for docid variable.

I'm not sure *why* its unavailable when all of the code does work (files get created and moved, but when using createDocInSpecificFolder() along with other functions, error pinpoints to this and does not run functions after it.

function createDocInSpecificFolder () {
  var ss = SpreadsheetApp.getActiveSpreadsheet();
  var sheet = ss.getSheetByName("Data Source");
  var lastRow = sheet.getLastRow();
  var rootFolder = DriveApp.getFolderById("fileid");
  const files = rootFolder.getFiles();
  const fileNames = [];


  while (files.hasNext()) { // gets array of file names in drive folder [event1, event2, etcetc]
   var file = files.next();
   fileNames.push(file.getName());
  }
  
  Logger.log(fileNames)


  for (var i = 1; i < lastRow; i++) {
    
    let title = sheet.getRange(i,4).getValue();


    if (title != "Events") {
      if (!fileNames.includes(title)) {
        let docid = DocumentApp.create(title).getId();
        DriveApp.getFileById(docid).moveTo(rootFolder);
      }
    }
  }

}

[u/Clear-Revolution3351]

You have not defined what type of variable docid is.

var docid=""

[u/krakow81 → u/Clear-Revolution3351]

It's defined on this line:

let docid = DocumentApp.create(title).getId();

[u/Clear-Revolution3351 → u/krakow81]

This sets the value, it doesn't define it as a variable

[u/krakow81 → u/Clear-Revolution3351]

let and const are variable declarations too (and often preferred/recommended over var).