Fallback if entityid is missing

[andreassolberg]

Thomasz:

Searching can break down if metadata has a missing entityId.
Obviously this should not happen, but perhaps it would be wise to ignore
problems with individual entries, so that the search still works. It
took me a bit of guessing to realise what went wrong. In principle the
responsibility for a particular entry will be outside of the domain of
the DJ manager, hence one black sheep should not break down the whole
thing. still you may argue that the metadata correctness should be
checked in advance, so I am not sure that this point really makes much
sense.