Bugfix, taking into account neutrals in the B final state

In my original implementation I did not take into account that the B decay can have daughters that are neutral. This lead to a nullptr when calling track() and a subsequent segfault.

Phys/FunctionalFlavourTagging/src/Utils/TaggingHelper.h

@@ -66,6 +66,7 @@ namespace TaggingHelper {
     if ( !p1.proto() || !p2.proto() ) return false;
     const LHCb::Track* t1 = p1.proto()->track();
     const LHCb::Track* t2 = p2.proto()->track();
+    if ( !t1 || !t2 ) return false;
 
     int          nCommonHits = t1->nCommonLhcbIDs( *t2 );
     int          norm        = std::min( t1->nLHCbIDs(), t2->nLHCbIDs() );