Return a 412 error if the content type is unknown
Return a 412 error if the content type is unknown

This is a more logical error than 500

isandlaTech/cohorte-herald,librallu/cohorte-herald,gattazr/cohorte-herald,librallu/cohorte-herald,gattazr/cohorte-herald,ahmadshahwan/cohorte-herald,librallu/cohorte-herald,isandlaTech/cohorte-herald,isandlaTech/cohorte-herald,ahmadshahwan/cohorte-herald,ahmadshahwan/cohorte-herald,gattazr/cohorte-herald