RPC: dumphdinfo should throw an error when wallet isn't HD (#2134)
RPC: dumphdinfo should throw an error when wallet isn't HD (#2134)

* Throws an RPCError `RPC_WALLET_ERROR` when the command `dumphdinfo` is called and the wallet is not HD

* Refactor based on @Udjin's post

dashpay/dash,nmarley/dash,crowning-/dash,biblepay/biblepay,thelazier/dash,nmarley/dash,crowning-/dash,biblepay/biblepay,ionomy/ion,ivansib/sibcoin,crowning-/dash,biblepay/biblepay,biblepay/biblepay,crowning-/dash,nmarley/dash,dashpay/dash,biblepay/biblepay,biblepay/biblepay,UdjinM6/dash,UdjinM6/dash,nmarley/dash,thelazier/dash,ivansib/sibcoin,nmarley/dash,crowning-/dash,ionomy/ion,dashpay/dash,nmarley/dash,ionomy/ion,dashpay/dash,biblepay/biblepay,crowning-/dash,ionomy/ion,thelazier/dash,ivansib/sibcoin,ionomy/ion,UdjinM6/dash,UdjinM6/dash,ionomy/ion,biblepay/biblepay,ivansib/sibcoin,thelazier/dash,thelazier/dash,ivansib/sibcoin,ivansib/sibcoin,UdjinM6/dash,dashpay/dash,nmarley/dash