LP#1683575 - Webstaff fix silent fail of bad barcodes in ItemStatus

LP#1683575 - Webstaff fix silent fail of bad barcodes in ItemStatus

This address the current issue in master, that causes bad barcodes
to fail silently.

To test
-------
[1] In the web staff client, go to Item Status and enter an item
    barcode that is not present in the database. Note that no
    warning message displayed.
[2] Apply the patch and repeat step 1. This tie, an 'Item Not Found'
    message is displayed.

Signed-off by: Cesar Velez <cesar.velez@equinoxinitiative.org>
Signed-off-by: Galen Charlton <gmc@equinoxinitiative.org>