fix: [json converter] fixed an issue if an expected key was not found
fix: [json converter] fixed an issue if an expected key was not found

- was only accessible due to another bug, but it's more graceful either way

MISP/MISP,SteveClement/MISP,MISP/MISP,MISP/MISP,SteveClement/MISP,MISP/MISP,MISP/MISP,SteveClement/MISP,SteveClement/MISP,SteveClement/MISP