Delete contact fails with no error message in the API


I am currently running a script to delete all my contacts in freeAgent and
have hit a slight API issue.

In freeAgent I have a contact which I assigned to a project, when I try to
delete it using the API I get a blank response back from freeAgent which
does not indicate anything, yet the contact still exists.

However if I log into freeAgent and try to delete it, it tells me that it
cannot be deleted as it is associated with a project, this makes perfect
sense to me but should the API not respond with a similar message so we can
handle it?

My code for reference:

$accessToken = 'MY-TOKEN-GOES-HERE';

$c = curl_init($contact);
curl_setopt($c, CURLOPT_HTTPHEADER, array(
    'Accept: application/json',
    'Content-Type: application/json',
    'Authorization: Bearer '.$accessToken
curl_setopt($c, CURLOPT_USERAGENT, 'SPCS LTD');
curl_setopt($c, CURLOPT_RETURNTRANSFER, true);

$result = curl_exec($c);
echo $result;

Thanks Aaron