This error in the log:
Exception in Airport::operator () (const TaxiwayPaths& paths)
Indicates something very serious: the scenery is basically illegal, a common mistake usually made by freeware authors, is to first exclude all default taxiways and parking spots in their scenery, then they redefine new parking without adding all taxiways again, which is a mistake, likely because the scenery was made with an old version of the SDK, which didn't check that ( current one does and won't let you compile a scenery like that )
Nothing we can do in GSX to fix it, because the data we get from the sim is just missing.