commerce_coupon_redeem_coupon_code() doesn't return error message.

Hello,

I meet a bug with the error message of commerce_coupon_redeem_coupon_code() function. The $error is no sent back.

I made the call like this:

   $error = '';
   if (!empty($code)) {
     $coupon = commerce_coupon_redeem_coupon_code($code, $order, $error);
      ...
   }

I am specially in a error case where my coupon is not available anymore, because a usage per person limit.
So I'm supposed to get back $error = "Unable to redeem coupon."

With the debugger I see that the function is suppose to return the message t('Unable to redeem coupon.'); by the referenced variable error. But after pass in the &drupal_static function, the $error variable is no longer a referenced variable and out of the function commerce_coupon_redeem_coupon_code() my $error variable take his value of empty again.

Add to this, this function calls the commerce_coupon_evaluate_conditions() function, wich use a access to protected member "Type":
$coupon_wrapper->type->value()
With this, my function always return TRUE => and she shouldn't !
I fixed with:
$coupon_wrapper->type()
It solved the error. This error occured 3 times in the commerce_coupon.module file.