> There isn't a standard convention for wrapping errors in Rust

I have to say that's the first time I've heard someone say Rust doesn't have enough return types. Idiomatically, possible error conditions would be wrapped in a Result. `foo()?` is fantastic for the cases where you can't do anything about it, like you're trying to deserialize the user's passed-in config file and it's not valid JSON. What are you going to do there that's better than panicking? Or if you're starting up and can't connect to the configured database URL, there's probably not anything you can do beyond bombing out with a traceback... like `?` or `.unwrap()` does.

For everything else, there're the standard `if foo.is_ok()` or matching on `Ok(value)` idioms, when you want to catch the error and retry, or alert the user, or whatever.

But ? and .unwrap() are wonderful when you know that the thing could possibly fail, and it's out of your hands, so why wrap it in a bunch of boilerplate error handling code that doesn't tell the user much more than a traceback would?