Prevent massive POST requests to error_url if error_url is down

[sweh]

If the URL, the client tries to submit the error to (error_url), is down, the plugin will try to send that error again and again to the server.

This fix prevents that.

I also changed the indentation from TAB to SPACE.

[remybach]

Hey, thanks for taking the time to actually submit a PR!

If I could please just request that you remove the commit changing the indentation? It's generally not good practice to push something as opinionated as that into someone else's repo. It also makes the PR diff impossible to read (not so difficult in this case as there's just one other commit, but in bigger PRs it can be a nightmare).

Also: could you take care of the case where what is an object (the other side of this if statement)?

[sweh]

Hi remybach,

I readded the tab indentation, so the real change is now more clear to review.

I was not able to reproduce the problem, if what is an object, so I suppose this side of the if statements does not need a fix.

Kind regards,
Sebastian

[remybach]

Great, thanks again @sweh!