title: How to add icon MUI Datatable?
body: <p>I'm using MUI DataTable and I'm trying to add &quot;Add Icon&quot; to the toolbar. I've tried this: <a href="https://github.com/gregnb/mui-datatables/blob/master/examples/customize-toolbar/CustomToolbar.js" rel="nofollow noreferrer">https://github.com/gregnb/mui-datatables/blob/master/examples/customize-toolbar/CustomToolbar.js</a> but it didnt work.
  Error:
  <strong>Element type is invalid: expected a string (for built-in components) or a class/function (for composite components) but got: undefined. You likely forgot to export your component from the file it's defined in, or you might have mixed up default and named imports.</strong>
  What's the proper and simplest way to add this icon? I have no idea how to do this.</p>