InvalidValueError: setLabel: not a string; and no text property

[temirfe]

I'm adding a custom markter:
$marker = new Marker([ 'position' => COORDINATES, 'title' => SOME_TITLE, 'label' => "14", 'icon' => MY_PNG, ]);

It shows my custom marker but no label, console says: InvalidValueError: setLabel: not a string; and no text property. If I do 'label' => "(14)" then it works but I don't need to show label with brackets.