fix #2524: add proper error message
fix #2524: add proper error message

wakiyamap/electrum-mona,dabura667/electrum,cryptapus/electrum,fireduck64/electrum,cryptapus/electrum,pooler/electrum-ltc,wakiyamap/electrum-mona,vialectrum/vialectrum,kyuupichan/electrum,vialectrum/vialectrum,spesmilo/electrum,molecular/electrum,vertcoin/electrum-vtc,spesmilo/electrum,fujicoin/electrum-fjc,romanz/electrum,romanz/electrum,digitalbitbox/electrum,asfin/electrum,pooler/electrum-ltc,asfin/electrum,dabura667/electrum,digitalbitbox/electrum,fireduck64/electrum,vialectrum/vialectrum,pknight007/electrum-vtc,kyuupichan/electrum,pknight007/electrum-vtc,wakiyamap/electrum-mona,pooler/electrum-ltc,vertcoin/electrum-vtc,wakiyamap/electrum-mona,neocogent/electrum,molecular/electrum,neocogent/electrum,fireduck64/electrum,dabura667/electrum,digitalbitbox/electrum,spesmilo/electrum,fujicoin/electrum-fjc,pknight007/electrum-vtc,vertcoin/electrum-vtc,molecular/electrum,digitalbitbox/electrum,dabura667/electrum,vertcoin/electrum-vtc,asfin/electrum,molecular/electrum,neocogent/electrum,spesmilo/electrum,fyookball/electrum,pooler/electrum-ltc,cryptapus/electrum,fujicoin/electrum-fjc,fyookball/electrum,pknight007/electrum-vtc,romanz/electrum,fyookball/electrum,kyuupichan/electrum,fireduck64/electrum