qt new_channel_dialog: fix None-handling for lnworker.suggest_peer()
qt new_channel_dialog: fix None-handling for lnworker.suggest_peer()

fixes https://github.com/spesmilo/electrum/issues/7931

spesmilo/electrum,pooler/electrum-ltc,spesmilo/electrum,pooler/electrum-ltc,spesmilo/electrum,pooler/electrum-ltc,pooler/electrum-ltc,spesmilo/electrum