Javascript AJAX request with 2 different return types

Is it possible to return 2 different types by an AJAX request?
I created a form with method post. The PHP file creates a PDF file what is returned to the JavaScript file and is automatically downloaded.

But I want also return an array to the same JavaScript file with messages like errors or a notice.

Can I do this in one call or is there a second call needed?

var form = event.target;
var formData = new FormData(form);
fetch(url,{
    method: 'post',
    body: formData
}).then(response => response.blob()).then(response => {
    const blob = new Blob([response], {type: 'application/pdf'});
    const downloadUrl = URL.createObjectURL(blob);
    const a = document.createElement("a");
    a.href = downloadUrl;
    a.download = formData.getAll("invoicenumber")+".pdf";
    document.body.appendChild(a);
    a.click();
});

PHP

$createPdf = new CreatePdf;
$response['msg'] = 'PDF is created!';
header('Content-Type: application/json; charset=UTF-8');
echo json_encode($response);