Bug 19771: Fix crashing in pending offline circulation actions list

Bug 19771: Fix crashing in pending offline circulation actions list

When the barcode is empty or invalid, an "Internal Server Error"
is triggered on the kohadev box.

TEST PLAN
---------
0) back up your database if you care about it.
1) Run the following commands:
    git checkout master
    git pull
    git checkout -b bug_19771 origin/master
    git bz apply 19771
   -- This should be quite uneventful. Standard promptings.
2) Continue to run the following commands:
    git checkout master
    reset_all
    sudo koha-shell -c bash kohadev
    ./misc/cronjobs/create_te_koc_db.pl --sqlite3
   -- This will create a borrowers.db in your current directory.
3) On the host where you intend on running the koct install it.
   -- https://sourceforge.net/projects/koha-oc/files/
      download and install.
4) get the borrowers.db file to your host where you installed koct
5) point koct at the file you downloaded
   Database -> Select Borrowers DB File
6) Create a .koc file with the following transactions.
    check in, check out, check in (bad barcode),
    pay fines (any non-zero amount).
7) Run the following commands:
    restart_all
   -- we want to make sure caching for plack isn't in the way.
8) In the staff client: Home -> Circulation
    -> Upload offline circulation file (.koc)
9) Choose the file created and click 'Upload file'.
10) Add to offline circulation queue.
11) View pending offline circulation actions
    -- This should die. Reading /var/log/koha/kohadev/plack-error.log
       should be the same error as comment #0.
       However, this was only the bad biblio error.
12) Run the following commands:
    git checkout bug_19771
    restart_all
13) Refresh staff client page.
    -- it should all come up.
14) Select the bad biblio line, and delete it.
15) Run the following commands:
    git checkout master
    restart_all
16) Refresh the staff client page.
    -- it should die. Same error as comment #0.
       This confirms the fine payment issue.
17) Run the following commands
    git checkout bug_19771
    restart_all
18) Refresh the staff client page.
    -- it should all come up.
19) run the koha qa test tools
20) if you backed up your database, restore it. :)

Signed-off-by: Mark Tompsett <mtompset@hotmail.com>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>