Pulling numbers between white space from email body into google sheets

I am trying to pull a 6 digit number(authentication code)between white space from the email body into a google sheet. "date, sender, and subject" are all populating in the google sheet correctly except "body", which is populating " [Ljava.lang.Object;@6f90342a ". Here is my full code and a screenshot of the email body.

 function getGmailEmails(){
      var input = ui.prompt('Label Name', 'Enter the label name that is assigned to your emails:', Browser.Buttons.OK_CANCEL);
      
      if (input.getSelectedButton() == ui.Button.CANCEL){
        return;
      }
      
      var label = GmailApp.getUserLabelByName(input.getResponseText().trim());
      var threads = label.getThreads();
      
      for(var i = threads.length - 1; i >=0; i--){
        var messages = threads[i].getMessages();
        
        for (var j = 0; j <messages.length; j++){
          var message = messages[j];
          if (message.isUnread()){
            extractDetails(message);
            GmailApp.markMessageRead(message);
            }
        }
        threads[i].removeLabel(label); //delete the label after getting the message    
      }  
    }
          function extractDetails(message){
          
          var emailData = {
            date: "Null",
            sender: "Null",
            subject: "Null",
            body: "Null",
          }
           regExp = /(\b(\d+)\b)/;
     
          emailData.date = message.getDate();
          emailData.subject = message.getSubject();
          emailData.sender = message.getFrom();
          main = message.getPlainBody();
          emailData.body = main.match(regExp);
  var activeSheet = SpreadsheetApp.getActiveSpreadsheet().getActiveSheet();
  
  var emailDataArr = [];
  
  for(var propName in emailData){
    emailDataArr.push(emailData[propName]);
  }
  activeSheet.appendRow(emailDataArr);

>Solution :

In your situation, I thought that the reason for your issue is due to that the return value from main.match(regExp) is an array. So, how about the following modification?

From:

emailData.body = main.match(regExp);

To:

var temp = main.match(regExp);
emailData.body = temp ? temp[0] : ""; // I thought that temp[1] can be also used.

Reference:

match()