Replace uses of `anyhow` with error types

[jplatte]

As can be seen in #863, there's not a lot of code that uses anyhow's anyhow! or bail!, and no code at all using its Context trait. Replacing those parts with more explicit error types would make it easier to handle the error cases, while dropping a dependency with a non-trivial amount of runtime magic and hardly complicating the code at all.

[jstarry]

Thanks @jplatte, it'd be great to do this before the next release since we're already making breaking changes for the error return types. Would you be willing to tackle this?

[jplatte]

Sure! :)

[jplatte]

Well... Despite the few locations in the code that use anyhow, an error type that could be used in its place would require to be convertible from multiple (de)serialization libraries error types AFAICT. I'm afraid I don't understand that part of yew well enough to implement this change.

[jstarry]

@jplatte ah yeah that's tricky. I think we will need to rework the format macros a bit. We could add an error variant to FormatError for each supported format. And those variants could be enabled/disabled using cfg feature flags. Then the macros could use the appropriate error variant for each format

[jplatte]

Sure.. Is there a general overview of the whole format things somewhere? That would help put things in perspective.

[jplatte]

Also, regarding yew::format::nothing::Nothing, what's its purpose? Why is something that represent nothing not convertible to an empty (byte) string and instead always fails conversion to that?

[jstarry]

Also, regarding yew::format::nothing::Nothing, what's its purpose?

I'm not a big fan of it, but it's used for GET requests currently. See here:
https://github.com/yewstack/yew/blob/master/examples/npm_and_rest/src/gravatar.rs#L47

Is there a general overview of the whole format things somewhere? That would help put things in perspective.

There isn't. Here's an issue: yewstack/docs#24

[bhgomes]

@jstarry Is there any update on this? I'd be willing to work on it.

[jplatte]

I've read in another issue that the whole format API is just going to be removed, so I think this is being worked on already basically.

[ranile]

I've read in another issue that the whole format API is just going to be removed, so I think this is being worked on already basically.

It has already been removed on master

[jplatte]

Looks like there is only a single use of anyhow in the main yew crate remaining 👍

https://github.com/yewstack/yew/blob/8fbb1a24cc5cfb9d29b76b106db624892ac898dc/packages/yew/src/utils/mod.rs