Make sure to populate the multidat error back up the stack

[okdistribute]

I was getting a module mismatch error but it was hidden under the sheets. I think in general it's nice to propagate fatal errors like this up the stack

[yoshuawuyts]

The error is still being propagated; if you look at the stack trace it should be clear (:

Also: I wasn't aware module mismatch errors were handled through a callback; I would've assumed they threw? That seems like a rather odd use of callbacks imo