Check for existence of hook_field_settings before merging into $form['field']

If you try to edit a field that does not contain a hook_field_settings implementation (for example, weburl), you'll receive the warning:

warning: array_merge() [function.array-merge]: Argument #2 is not an array in D:\xampp\htdocs\hackergames.net\modules\cck\content_admin.inc on line 530.

about the following line:

$form['field'] = array_merge($form['field'], module_invoke($field_type['module'], 'field_settings', 'form', $field));

This is a simple patch that wraps this line in a if (module_hook()) check first.