feat(typed_header_rejection): add is_missing utility to the reason

[joshuachp]

Motivation

It's hard, when creating your own extractor, to check if a TypedHeader is missing or there was an actual error. The TypedHeaderRejectionReason doesn't/can't implement PartialEq since it include the headers_core::Error variant, so you need to add a match to check.

match typed_header {
   Ok(_) => todo!(),
   Err(err) if matches!(err.reason(), TypedHeaderRejectionReason::Missing)  => todo!(),
   Err(_) => todo!()
}

Solution

Add a utility function to check if the TypedHeaderRejection is missing. Example:

match typed_header {
   Ok(_) => todo!(),
   Err(err) if err.is_missing() => todo!(),
   Err(err) => todo!()
}

[davidpdrsn]

Looks good! Wanna update the changelog as well?

[joshuachp]

Updated the CHANGELOG