Switch to a concrete Error type

[belak]

Please note that this is specifically a PoC to replace usage of Box<dyn std::error::Error + Send + Sync + 'static> with a concrete surf::Error type.

There are a few things yet to figure out:

• Documentation for surf::{Result, Error}
• Whether or not the Error variants should be exposed to the end user or if they should be hidden. I went with hiding it because it's similar to anyhow::Error.
• When to return a surf::Error vs alternatives (like serde_json::Error) or if surf::Error should always be used
• How errors should be displayed. Should they be wrapped or displayed as-is?

The main Error implementation is in error.rs and is also exported at the root of the crate.

This is an alternative to simply re-exporting anyhow::Error and would be another method of fixing #86.

[zkat]

hey @Fishrock123 @yoshuawuyts can we take this one? I think this would solve the error issue nicely.

@belak I notice you have a lot of conflicts. Are you ok with fixing them, or would you rather someone else do it, at this point?

[Fishrock123]

At a glance this sounds right to me, that’s what Tide does.

[belak]

I'd be happy to work on this, but it might take a few days since I've got a bunch of other stuff going on

[Fishrock123]

Ok so I wrote that and these comments without 100% realizing it until after, but what I said here actually happened already in c8366fb. I thought something was a little off.

(Also @zkat ^)

So... this isn't necessary anymore. Thanks anyways though.

one part hasn't been 100% completed though, if you'd like to pick it up still: convert all Result<T, Err> to surf::Result<T>.

[Fishrock123]

This probably doesn't need to exist. Ideally this would just using http_types::Error instead: https://docs.rs/http-types/2.3.0/http_types/struct.Error.html

(It's implemented like this: https://github.com/http-rs/http-types/blob/master/src/error.rs)

[Fishrock123]

Also with http_types::Error this shouldn't be necessary, because it wraps the errors and allows you to check downcasts, like so:

match surf::get(url).await {
    Ok() -> (),
    Err(error) -> {
        if let Some(&url_err) = error.downcast_ref::<UrlError>() {
            // ...
        } else if let Some(&json_err) = error.downcast_ref::<JsonError>() {
            // ...
        }
    }
}

[Fishrock123]

This already exists from the recent-ish ac215cb

[Fishrock123]

Closing since as noted above, the better change would have been a switch to http_types::Error, which was already done in April in c8366fb!