Getting bad request on updating contact

[nafeeurr-lgtm]

$this->client->contacts->update("abcd", [
    'custom_attributes' => ['nickname' => 'Nick Guichi'],
    'email' => 'nick@example.com',
]);
return;

I have the existing contact id.
"intercom/intercom-php": "^4.5",

There is no other information from the Exception. Just Bad Request. What could be the reason?

[nafeeurr-lgtm]

If we want to change custom_attributes then it's giving Bad request.

Like the above example. But if we want to change the email and name, it's working perfectly.