Yes, I want to send a 'fake' backtrace, since there is still useful info in the top level error object, and I'm also attaching useful user data (like the unparsed backtrace, since there's so many bugs in the client side parsing). I'm also fine with allowing errors without backtraces: I ran into the same problem when writing a Haskell client. I'm not the biggest Ruby hero though, and Rails, well, that's another thing entirely.