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 is inactive and the other node acts to close the channel. If fees are high at the time, the fees paid will be high to resulting in a significant loss.
I'm not still fully certain this is a bug or the node force closing, but can't say why it's happened multiple times to you.
This is obviously a bug in the Electrum software which has happened to me multiple times, and others as well. This bug is quite serious as it not only breaks the functionality of lightning, but also results in losses because of high fees (by "high" I mean relatively to the fees that are considered "normal" at the time)
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.
I'm quite surprised Electrum is the only desktop wallet which supports lightning. Hope what other wallets follow. For me, mobile wallets are not the way - a phone can be easily lost or stolen, so mobile wallet is good to hold only tiny amounts which makes the whole thing cumbersome (I would have to constantly replenish the mobile wallet to continue transacting)