Fix error in ALP->gammagamma line
FIND_IN_TREE functor is used to check whether any of the decay products of the signal are matching with other extra particles (see definition here).
~FIND_IN_TREE requires then that every decay products of the signal does not match with other extra particles
This check is done comparing the TRACK property of a PROTOPARTICLE associated to the two particles compared (see this line). This does not exists for neutral particles.
This quick fix is meant to be just temporary, only for that line, and to include with the next release to remove the redundant error messages in the log of the HLT2 processing.
A check could be introduced offline to remove the signal photons from eventually being persisted, or it could be introduced online with some proper functor that make the analogous FIND_IN_TREE functionality available for neutrals
Resolves #971 (closed)