This is a peculiar case. If a channel close doesn't happen voluntarily then a force close can happen in the event when one of the channel peer's node is inactive and the other acts to close the channel (if fees are high at the time, the fees paid will be). I'm not still certain this is a bug or the node force closing, but can't say why it's happened multiple times to you.
Is there any other open-source Electrum wallet available for Windows or Linux desktops?
Can't think of any. Any which fits the former part of your requirement will be limited to mobile.