raise a 404 error if the json file is not found
raise a 404 error if the json file is not found

radiasoft/sirepo,radiasoft/sirepo,radiasoft/sirepo,mkeilman/sirepo,mrakitin/sirepo,radiasoft/sirepo,radiasoft/sirepo,mrakitin/sirepo,mrakitin/sirepo,mkeilman/sirepo,mkeilman/sirepo,mrakitin/sirepo,mkeilman/sirepo