FR: possibility to launch it "in the background" and have it appear only in case of errors

[thiswillbeyourgithub]

Hi!

Eruda has been a huge time saver for me so thank you to start with!

The only issue I have with it is that often I put in my code that in case of error, we should launch eruda. But then sometimes it misses the first few warnings/errors. So I usually enable the Always Display if Error Occurs setting and try to redo what triggered the issue.

So:

1. If the issue happens right away on page load it can be an issue to trigger eruda at the right time.
2. I can't seem to set the default setting to always open on errors, I always have to set it manually. And the doc is not very clear.

Request:

1. Can you consider having a way to set the Always Display if Errors Occurs from the js code directly? I read the docs and couldn't find a details list of settings.
2. Is there a way to run eruda without having the floating button appear until an error appeared? I would very much like that as I don't mind always loading the code when I am debugging stuff but often mind having the floating icon even though I know I won't user it until an error happens.

Thanks!