`Error detected while processing - not an open channel` if server dies

[OJFord]

• Did you upgrade to latest plugin version? Yes
• Did you upgrade to/compile latest binary? Run shell command
  bin/languageclient --version to get its version number. languageclient 0.1.161
• (Neovim users only) Did you check output of :checkhealth LanguageClient? N/A
• Did you check troubleshooting? Yes

Describe the bug

Any LanguageClient command (including LanguageClientStop & LanguageClientStart) fails with an error like:

Error detected while processing function LanguageClient#startServer[6]..LanguageClient#Call[22]..LanguageClient#Write:
line 11:
E906: Not an open channel

If the (STDIO only?) langauge server exits outside of it's control.

Environment

• neovim/vim version (nvim --version or vim --version): VIM - Vi IMproved 8.2 (2019 Dec 12, compiled Jan 16 2022 12:09:56)
• This plugin version (git rev-parse --short HEAD): a42594c
• This plugin's binary version (bin/languageclient --version): languageclient 0.1.161
• Minimal vimrc content (A minimal vimrc is the smallest vimrc that could
  reproduce the issue. Refer to an example here): any
• Language server link and version: any

To Reproduce

• Run vim & languageclient
• :!kill (or kill from another shell) the language server
• Try to call formatting, stop server, start server, etc.

Current behavior

Error detected while processing function LanguageClient#startServer[6]..LanguageClient#Call[22]..LanguageClient#Write:
line 11:
E906: Not an open channel

Expected behavior

Good: LanguageClientStop shouldn't care IMO, should just close down itself & if server already down that's no problem; LanguageClientStart should start it again if not already running.

Better: Automatically restart on any command; only error if it fails to start up again?

Screenshots

Additional context

I've perhaps most often hit this with VLS (Vue) spinning it's wheels and making vim hang entirely; short of killing the vim instance all I can do is kill the language server and live with the broken languageclient. (Because it's unresponsive, so I can't LanguageClientStop.) Though it has also happened where the server has just died for whatever other reason that wasn't me killing it.