Bug 20623: Fix basket group PDF when itemtype not itemtype table

Bug 20623: Fix basket group PDF when itemtype not itemtype table

When an item has an itemtype not in the itemtype table. Trying to fetch
it's description lead to an error.
Using authorized values like ccode to populate the itemtypes of the
biblioitems (instead of the itemtype table) can lead to such data.
Or importing records with invalid itemtype codes. Koha doesn't do enough
checks at import to at least warn about these issues.

== Test plan ==
1. first we need an item with an itype not in the item_types table
   1. download a record as MARCXML
   2. find it's item type in administration; and the related code
   3. open the MARCXML file and search for occurences of the code
        and replace them by some non-existing value like "FOOBAR"
   4. also change the barcode so it won't be ignored because
        it's a duplicate
   5. also change the title to easily find it later in the search
   6. tools → "Stage MARC records for import"
   7. upload your file
   8. "stage for import"
   9. click "Manage staged records"
        You should end on the page related to your staged record
   10. "Import this batch into the catalog"

2. now we need it in a basket group
   1. have/create a active budget
   2. have/create a fund
   3. have/create a vendor with minimal info
   4. create a basket with minimal info
   5. add our imported item to the basket
        for example search it by name
   6. go to the basket. URL should be
      /cgi-bin/koha/acqui/basket.pl?basketno=XXXXX
   7. close this basket
        and tick "Attach this basket to a new basket group with the same name"
   8. you will end up in the basket groups lists
   9. go to the "closed" tab
   11. go to the basket group
          your vendor page => Basket groups => Closed

3. export as PDF, it should fail (internal server error)
     this is the bug (no kidding ^_^)
4. apply this patch
5. reexport the basket as PDF
6. it should work
7. create an item type (in administration)
     that has the same code as the one that you put in the MARCXML
8. reexport the basket as PDF
9. check that in the PDF that the description is here:
     table at the bottom of the document → "Document" column

Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>