Google Apps Script generates float instead of Integer (but not always!?!)

I have a custom script in a Purchase Requests spreadsheet. It generates new tabs and adds links from the new tab to 'register' (the first tab) in order to summarize the data.

Unfortunately, the tab name often gets generated in float format (206.0) instead of integer format, so the tab name references, which are always in integer format, don't work. I can't figure out why the float is appearing. It doesn't happen on every computer we try it on, only most, which makes it even more mysterious.

I've tried different methods for coercing it to an integer but haven't found a solution. All suggestions gratefully welcomed.

function newPR(e) {
  // First, set up the variables we'll need
  var ui = SpreadsheetApp.getUi()
  var ss = SpreadsheetApp.getActiveSpreadsheet();
  var sheets = SpreadsheetApp.getActiveSpreadsheet().getSheets();  
  var sheet = sheets[0];
  var templateSheet = sheets[1];
  var highestPurchaseRequest = sheets[3];
  var today = new Date();
  var requestCount = sheet.getRange(6,1).getValue();  //getRange: row, column
  var lastRequestTab = parseInt(highestPurchaseRequest.getName(),10);
  var checkNeeded = ( requestCount != lastRequestTab );
  var loopCount = 0;
  /* Before starting, check whether the highest request number matches the 
     name of the highest estimate tab created so far. If not, try to fix it a few 
     times.  If you can't fix it automatically, flag an error and ask the user to 
     sort it out.
  */
  if( checkNeeded ) {
    while( loopCount < 100 && checkNeeded ) {
      if( requestCount <= lastRequestTab ) {
        requestCount++;
      } else {
        checkNeeded = false;
      }
      loopCount++
    }
    if( checkNeeded ){
      ui.alert("Something went wrong!",'The highest Purchase Request listed on the Summary tab is lower than leftmost Purchase Request tab in the spreadsheet.\n\nI\'ve tried to fix this automatically but haven\'t been able to. Maybe someone dragged tabs into a different order accidentally? The order should be: Register, TemplatePO, TemplateCS, Highest-numbered-request.\n\nPlease correct it and retry. ',ui.ButtonSet.OK);
      return;
    }
  }
    /* Everything looks good, so create a new sheet using "templatePO" as the template, 
       increment the request number and use it to name the new sheet; fill in the 
       current date & estimate number at the top 
    */
    requestCount = ++requestCount >> 0;
    ss.insertSheet(requestCount.toString(), 3, {template: templateSheet});
    // Now that it's made, we need another variable to store a reference to the new sheet
    var newSheet = SpreadsheetApp.getActiveSheet();
    newSheet.getRange(5,9).setValue( today );
    
    // Switch to the summary sheet and add links to the new data
    ss.setActiveSheet( sheets[0] );
    ss.insertRowBefore(6);
    var newCells = sheet.getRange(6,1,1,9);
    // Data from: PR# in I2, Date in I5, From in D4, For/Description in D5, Total in D7, sent in K2, received in K11, Notes in K5
    var requestData = [ [ requestCount, "='" + requestCount + "'!I5", "='" + requestCount + "'!D4", "='" + requestCount + "'!D5", "='" + requestCount + "'!K2", "='" + requestCount + "'!K11", "='" + requestCount + "'!D7","",""] ]
    newCells.setFormulas( requestData );
  
    // Switch back to the new sheet & get ready for user input
    ss.setActiveSheet( newSheet );
    newSheet.setActiveSelection("D5");
}