Fix a check for an empty mediaType
Fix a check for an empty mediaType

We need it for the old attachments.

dsumin/freefeed-html,pepyatka/pepyatka-html,dsumin/freefeed-html,epicmonkey/pepyatka-html,FreeFeed/freefeed-html,epicmonkey/pepyatka-html,FreeFeed/freefeed-html,SiTLar/pepyatka-html,pepyatka/pepyatka-html,SiTLar/pepyatka-html