fix: invalid window id errors

[jghauser]

Hey! Thanks a lot for this plugin! I've run into the 'invalid window id' errors reported in #4 and #16 (and maybe also #2). In this PR I've solved them (as far as I can tell) by simply checking whether the window ids are valid before attempting to do anything with them. Let me know if this is useful to the plugin or if you'd like me to improve it in some way.

Given that it's just checking for the validity of the window ids, I don't think it should make anything worse at least :).

[EDIT: If anyone reading this wants a somewhat useable fork, feel free to check out mine. It's got all PRs from the original repo merged and some additional fixes.

EDIT2: I now use tint.nvim instead and stopped maintaining the fork.]

[gwd999]

same errors when using shade with Nvim-R Plugin

[jghauser]

@gwd999 are those errors solved with this PR?

[ambadyanands]

@jghauser Thanks a lot for fixing this. I hope @sunjon is doing good and will merge this when they're back. :heart:

[ananthb]

I have the same issue with rmagatti/auto-session. Does this plugin need to be handled separately or will this PR also cover that?