Use void to indicate that parsing will never return an Err

[aidanhs]

Make it more explicit, both in documentation and the type system, that parsing will never error.

(I would've used ! but it's unstable)

[alkis]

It seems the ! type is stabilized for this usecase. Do you want to update the PR?

[jonathanstrong]

hey @aidanhs, thanks for submitting a pull request. I realize it has been quite some time since you submitted this, and you are only now getting a response. I was recently added to the project and have begun reviewing outstanding pull requests.

Since ! has been stabilized, I believe that is a much better choice. If you don't mind updating the pull request, I would appreciate it.

One thing I need to consider is whether this change requires a new major version. On the one hand, it is a change to the external api, on the other hand, it's hard to imagine it being incompatible with anyone's code.