I had run into the same thing a while ago. The error message is not helpful at all, but I fixed it (with help from the elm Slack channel) by changing the port signature from
port portName : X -> Cmd Msg to port portName : X -> Cmd msg (note the lowercase `msg`, which makes it generic). Cheers, --gera. -- You received this message because you are subscribed to the Google Groups "Elm Discuss" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
