Smooth recovery from invalid configs

[nik-rev]

If you have an invalid config key, your entire config will be disabled

But this can be really annoying for people who have custom PRs merged into their personal forks. I currently have #11285 merged and have the following config set:

[keys.normal.space]
E = "file_browser"

But since this is only valid in that PR and not on master, everytime I try to use a different branch that doesn't have my config my entire setup stops working:

So what I usually do is comment out that part of config every time. Since I have quite a lot of branches for Helix, and test various things out time to time, this ends up being a common procedure

Imo, it would be better for user experience if you still got the Bad config warning and forced to press enter, but at least your other settings should continue to work.