It looks like this was CLOSED WONTFIX: How can we _possibly_ know that
upon an error, the developer might want us to send an indication of that
error??!!1! Snark aside (mine and his): it looks like there's not a
great way to enable sane error behavior globally :/
https://caddy.community/t/handling-errors-globally/17174/2
In the future, I should probably make this a snippet or something.