how to see errors on remote hosts?

I'm using Webistrano, a web-based wrapper for Capistrano. When I do
the cap deploy, I often get an error on the remote server that stops
Capistrano but the contents of the error are not shown. I seem to
remember there being a snippet of code that I could put into my
capfile that would send back stderr when a command failed on the
remote server. Otherwise, I have to rerun the command myself on the
server, just to start debugging the problem.

Can anyone point me to this snippet, or edify me how I might configure
cap to handle this? I feel like I may be missing something, because
displaying error text is a pretty basic/essential function.

Thanks in advance!
-Jason