JavaScript runtime error: Unable to get property 'className' of undefined or null reference

I created a data table on an HTML table with the following code.
$('#ContractsView').dataTable({
"aaSorting": []
});

This runs fine when the table is empty

When this code runs for a table which has rows I get this error:

Unhandled exception at line 669, column 8 in https://localhost:44308/Scripts/jquery.dataTables.js

0x800a138f - JavaScript runtime error: Unable to get property 'className' of undefined or null reference

At this code
/* Classes */
if ( bClass )
{
nCell.className += ' '+oCol.sClass;
}

I have two other html tables which are entered the same way before hand.

$(document).ready(function () {
$('#FundDocsView').dataTable({
"aaSorting" : []
});
$('#PRView').dataTable({
"aaSorting": []
});
$('#ContractsView').dataTable({
"aaSorting": []
});
});

They run with no problem. The ContractsView tables runs fine when there is no data,
but as soon as the table is populated this error occurs
I am confused what would cause this error.