controllers.flights: return 404 in json() if no trace available
controllers.flights: return 404 in json() if no trace available

Turbo87/skylines,Harry-R/skylines,dkm/skylines,RBE-Avionik/skylines,skylines-project/skylines,Turbo87/skylines,snip/skylines,dkm/skylines,skylines-project/skylines,snip/skylines,RBE-Avionik/skylines,dkm/skylines,shadowoneau/skylines,Harry-R/skylines,Turbo87/skylines,shadowoneau/skylines,shadowoneau/skylines,TobiasLohner/SkyLines,kerel-fs/skylines,dkm/skylines,Harry-R/skylines,kerel-fs/skylines,TobiasLohner/SkyLines,shadowoneau/skylines,Turbo87/skylines,skylines-project/skylines,snip/skylines,skylines-project/skylines,Harry-R/skylines,RBE-Avionik/skylines,RBE-Avionik/skylines,kerel-fs/skylines,TobiasLohner/SkyLines