[Twisted-web] Error output for bad deferred method signatures?

[Tommi Virtanen]

Lenny G Arbage wrote:
> 'test(respOrErr, msg)'.  What isn't clear [to me] is
> why this doesn't produce an error upon firing the
> deferred, but instead produces an error when the
> reactor shuts down [via ctrl-c], which could be hours
> later.

It does. But as the error happens inside your Deferred
chain, it will sit there waiting for an errback to be
added, which would handle it. At shutdown you see debug
output telling you forgot to handle errors in your
Deferred chain.

Add d.addErrback(log.err) after all the other deferred
handling and errors in the deferred chain will cause log
output and will not get complained about.