Right now it produce an image event because Bliki produce an image event for any
syntax (which is also what is documented in https://www.mediawiki.org/wiki/Help:Images).
It practice it looks like
syntax is more an universal extensible viewer than an image. Problem is that we don't really have an equivalent in rendering events.
Not sure what is the best here, the simplest would probably be to have some list of known image extensions and if it's not one of them then produce an attachment event instead. Ideally with would need something like a view macro.