qt: channel_details: prevent crash on stuck SENT htlc
qt: channel_details: prevent crash on stuck SENT htlc

pooler/electrum-ltc,wakiyamap/electrum-mona,wakiyamap/electrum-mona,pooler/electrum-ltc,spesmilo/electrum,wakiyamap/electrum-mona,pooler/electrum-ltc,spesmilo/electrum,spesmilo/electrum,vialectrum/vialectrum,vialectrum/vialectrum,pooler/electrum-ltc,spesmilo/electrum,vialectrum/vialectrum,wakiyamap/electrum-mona