Copying Google Sheets table to Google Document - Error with Boolean cells

I am very new to programming google app script, just trying to make some custom function. Sorry if this question is too basic...

I was following a tutorial to copy a table from Google Sheets into Google document but the exact same code the instructor was using did not worked for me.

I was getting this error:

Exception: The parameters (number[]) don't match the method signature for DocumentApp.Body.appendTable.

The simplified version of the code is:

function fun4(){
  var ss = SpreadsheetApp.openById('17-23aFf6mN5oQrKNwNDy3Zh24_foTN5mXzNkjvd3V5w');
  var sheet = ss.getSheets()[0];

  var doc = DocumentApp.create('Sample Sheet Data');
  var body = doc.getBody();

  var numLines =  sheet.getLastRow();
  var numColumns = sheet.getLastColumn();

  var rowData = sheet.getRange(1, 1, numLines, numColumns).getValues();
  console.log(rowData);

  var table = body.appendTable(rowData);   // ERROR IN THIS LINE
  table.getRow(0).editAsText().setBold(true);
}

After some search I found that the problem was caused by the last column containing Boolean values and changed .getValues() to .getDisplayValues().

It is working now but I am very confused... How it was working in the instructor code but not in mine? Why did not work if the output looks to be in the same format (double array?)

Code: (Gives an error when I append the table to doc , but worked in the instructor video)

  var rowData = sheet.getRange(1, 1, numLines, numColumns).getValues();
  console.log(rowData);

Output:

11:36:05 AM Info    
[ [ 'NAME', 'EMAIL', 'AGE', 'ACTIVE' ],
  [ 'Alex', 'alex@gmail.com', 50, true ],
  [ 'Brian', 'brian@gmail.com', 34, false ],
  [ 'Julian', 'julian@gmail.com', 42, true ],
  [ 'John', 'john@gmail.com', 24, false ] ]

Code:

  var rowData = sheet.getRange(1, 1, numLines, numColumns).getDisplayValues();
  console.log(rowData);

Output:

11:36:05 AM Info    
[ [ 'NAME', 'EMAIL', 'AGE', 'ACTIVE' ],
  [ 'Alex', 'alex@gmail.com', '50', 'TRUE' ],
  [ 'Brian', 'brian@gmail.com', '34', 'FALSE' ],
  [ 'Julian', 'julian@gmail.com', '42', 'TRUE' ],
  [ 'John', 'john@gmail.com', '24', 'FALSE' ] ]