Fix signature verification stoplight triggering on non-timeout errors (mastodon#9617)

Author: Gargron

app/controllers/concerns/signature_verification.rb

@@ -47,6 +47,7 @@ def signed_request_account
       .with_fallback { nil }
       .with_threshold(1)
       .with_cool_off_time(5.minutes.seconds)
+      .with_error_handler { |error, handle| error.is_a?(HTTP::Error) ? handle.call(error) : raise(error) }
 
     account = account_stoplight.run