Replace err-derive with thiserror
The err-derive crate is now depreciated, and the author currently recommends moving to thiserror
Some info:
Currently, the error dervies that use err-derive take up about 149 lines of code. thiserror although not a drop-in replacement is close to it, and it shouldn't be too difficult to transfer over.
Info on switching over from err-derive that I've found out
#[derive(Error) still works as normal
An example of something that needs to change is any #[error(display = "whatever")] lines. This actually becomes easier with it looking like #[error("whatever")]. Any sort of fields that are needed from the struct or tuple are done very similarly.
More information on thiserror can be found on docs.rs here. I recommend we just base on "1.0" and let any minor versions update as needed.