UNTRANSPILED_SYNTAX shows the following message:

[UNTRANSPILED_SYNTAX] Error: JSX syntax should be transpiled before bundling. Found untranspiled JSX in "../some/file/path"

It is not clear what the user is expected to do.
Is this a problem on the user side? In that case, what should the user do?
If this is an internal error that indicates a bug, I guess this should be a UNHANDLED_ERROR as that would show that this is a bug in Rolldown.