Cleanup and finalise error handling for WitnessCoinbaseInfoIsValid.
Cleanup and finalise error handling for WitnessCoinbaseInfoIsValid.

nlgcoin/guldencoin-official,nlgcoin/guldencoin-official,nlgcoin/guldencoin-official,nlgcoin/guldencoin-official,nlgcoin/guldencoin-official,nlgcoin/guldencoin-official