First time visitors direct linking to a node causes PDOException General Error

Hi,

I'm using your module which i find pretty and useful, i've set it up correctly, works fine for logged and anonymous users BUT only after the first visit on the node.
That is a major problem if you consider that if a never-visited-user clicks on a search engine result and navigates to my node(s), for the first time the site will fail giving the following error:

PDOException: SQLSTATE[HY000]: General error: 1366 Incorrect integer value: '' for column 'sid' at row 1: INSERT INTO {recently_read} (sid, entity_id, type, language, timestamp) VALUES (:db_insert_placeholder_0, :db_insert_placeholder_1, :db_insert_placeholder_2, :db_insert_placeholder_3, :db_insert_placeholder_4); Array ( [:db_insert_placeholder_0] => [:db_insert_placeholder_1] => 1010428 [:db_insert_placeholder_2] => node [:db_insert_placeholder_3] => en [:db_insert_placeholder_4] => 1374834711 ) in recently_read_entity_view() (line 68 of /MY_WEBSITE_FOLDER/sites/all/modules/recently_read/recently_read.module).

Keep in mind that i have already tried all the "stable" versions of your module. The above message comes from the dev one.

The problem is that in that particular line of recently_read.module file, the function session_api_get_sid() returns nothing and that causes the following query to fail:

$status = db_merge('recently_read')
                  ->key(array(
                    'sid' => session_api_get_sid(),
                    'entity_id' => $entity->{$info[$type]['entity keys']['id']},
                    'type' => $type
                  ))
                  ->fields(array(
                    'type' => $type,
                    'language' => $langcode,
                    'timestamp' => REQUEST_TIME,
                  ))
                  ->execute();

Until you suggest me (and anyone else facing the same issue) a solid solution, i've came up with a little bit tweaking code in that point.

Please help!