Google Script: Failed request and returned code 500

I'm experiencing an error called code 500. The script works fine if I'm using it in the owner account, but if I'm going to open the file as a user/editor, the code 500 error shows. Here is the link to the sample spreadsheet that I'm working on. I tried asking here but seems like it is a little complicated so I created a new single spreadsheet so that it can be easily identified the error.

Here's the code

function doGet(e) {
  this[e.parameter.run](e.parameter.sheetName || null);
  return ContentService.createTextOutput('It worked!');
}

function HideRows() {
  const activeSheet = SpreadsheetApp.getActiveSheet();
  const url = ScriptApp.getService().getUrl();
  UrlFetchApp.fetch(url + "?run=script_HideRows&sheetName=" + activeSheet.getSheetName(), {headers: {authorization: "Bearer " + ScriptApp.getOAuthToken()}});
// DriveApp.getFiles()  // This is used for automatically detecting the scope of "https://www.googleapis.com/auth/drive.readonly". This scope is used for the access token.
}

function showRows() {
  const url = ScriptApp.getService().getUrl();
  UrlFetchApp.fetch(url + "?run=script_showRows", {headers: {authorization: "Bearer " + ScriptApp.getOAuthToken()}});
  Browser.msgBox(url + "?run=script_showRows");
}

var startRow = 6;
var colToCheck = 2;

// This script is the same with your "HideRows".
function script_HideRows() {
  var sheetNames = ["MS_Q1", "MS_Q2", "MS_Q3", "MS_Q4", "SUMMARY"];  // Please set the sheet names here. In this case, 4 sheets are used.
  var ss = SpreadsheetApp.getActiveSpreadsheet();
  ss.getSheets().forEach(sheet => {
    var sheetName = sheet.getSheetName();
    if (sheetNames.includes(sheetName)) {
      if (sheetName == "SUMMARY") {  // When the sheet is "SUMMARY", the start row is changed.
        startRow = 7;
      }
      var numRows = sheet.getLastRow();
      var elements = sheet.getRange(startRow, colToCheck, numRows).getValues();
     
      for (var i=0; i < elements.length; i++) {
        if (shouldHideRow(sheet, i, elements[i][0])) {
          sheet.hideRows(startRow + i);
        }
      }
      // Hide the rest of the rows
      var totalNumRows = sheet.getMaxRows();
      if (totalNumRows > numRows)
        sheet.hideRows(numRows+1, totalNumRows - numRows);
    }
  });
}

// This script is the same with your "showRows".
function script_showRows() {
  // set up spreadsheet and sheet
  var ss = SpreadsheetApp.getActiveSpreadsheet();
//  var ss = SpreadsheetApp.getActiveSpreadsheet(),
  var sheets = ss.getSheets();

  for(var i = 0, iLen = sheets.length; i < iLen; i++) {
    // get sheet
    var sh = sheets[i];

    // unhide columns
    var rCols = sh.getRange("1:1");
    sh.unhideColumn(rCols);

    // unhide rows
    var rRows = sh.getRange("A:A");
    sh.unhideRow(rRows);
  }
};

function shouldHideRow(ss, rowIndex, rowValue) {
  if (rowValue != '') return false;
  if (ss.getRange(startRow + rowIndex, colToCheck, 1, 1).isPartOfMerge()) return false;
  if (ss.getRange(startRow + rowIndex + 1, colToCheck, 1, 1).isPartOfMerge()) return false;
  return true;
}