Use of reply and reject outside of manual needs better error

[bdemann]

If we could make a nice polished error for when you use reply and reject outside of manual. Right now it gives an error like this

The replica returned a rejection error: reject code CanisterError, reject message Error from Canister bkyz2-fmaaa-aaaaa-qaaaq-cai: Canister violated contract: ic0.msg_reply_data_append: the call is already replied..
This is likely an error with the compiler/CDK toolchain being used to build the canister. Please report the error to IC devs on the forum: https://forum.dfinity.org and include which language/CDK was used to create the canister., error code None

And we don't feel like that error really explains what is going on unless you are very aware of how replying and rejecting works. It's not great for newcomers