This seems like a bandaid that gets around the real problem: binary types don't have a charset. We use mime-db (or did, anyway) to generate the mime.types file, and it does include if there's a charset. Perhaps we could write this such that we add the charset for types which support it? https://github.com/jshttp/mime-db#data-structure https://github.com/jshttp/mime-db/blob/master/db.json

Only text-based files have a charset, all others are binary, so if we can solve this for all binary formats then we can also solve this for wasm.

Only text-based files have a charset, all others are binary...

[insert now why didn't I think of that emoji]
Excellent point @parkr. So, should Jekyll's mime.types include a new cell containing charset data for applicable types?