Unsupported format doesn't throw exception anymore

[alex88]

Hello,

I'm using the dev-master version of the bundle and now trying to set 'html' as format doesn't throw the usual UnsupportedFormatException but gives "None has no value"

Maybe i've something wrong in the config?

Old serializer.php had

/**
 * @return VisitorInterface
 */
public function getDeserializationVisitor($format)
{
    if (!isset($this->deserializationVisitors[$format])) {
        throw new UnsupportedFormatException(sprintf('Unsupported format "%s".', $format));
    }

    return $this->deserializationVisitors[$format];
}

/**
 * @return VisitorInterface
 */
public function getSerializationVisitor($format)
{
    if (!isset($this->serializationVisitors[$format])) {
        throw new UnsupportedFormatException(sprintf('Unsupported format "%s".', $format));
    }

    return $this->serializationVisitors[$format];
}