Typescript 4.9.4: Types of property 'authenticatorAttachment' are incompatible

[uwolfer]

With Typescript 4.9.4, I am getting the following error. With TS 4.8.4, no such error is thrown.

node_modules/@github/webauthn-json/dist/types/basic/json.d.ts:9:18 - error TS2430: Interface 'PublicKeyCredentialWithClientExtensionResults' incorrectly extends interface 'PublicKeyCredential'.
  Types of property 'authenticatorAttachment' are incompatible.
    Type 'string | null | undefined' is not assignable to type 'string | null'.
      Type 'undefined' is not assignable to type 'string | null'.

[lgarron]

Thanks for the report! Unfortunately, this is a recurring problem with a living spec and multiple browser implementations.

In particular, it seems that the field is required (but nullable) in the spec but authenticatorAttachment is not available in Firefox 109 (or as of Firefox 111.0a1 nightly) on macOS, and I can't even find a bug for it: https://bugzilla.mozilla.org/buglist.cgi?quicksearch=authenticatorAttachment

Some options:

1. Make PublicKeyCredentialWithClientExtensionResults extend Omit<PublicKeyCredential, "authenticatorAttachment"> instead of PublicKeyCredential.
2. Publish a package with types that are incompatible with Firefox.
3. Try to convince TypeScript to mark the field as optional for now.
4. Get Firefox to add support.

Option 2 is probably the least surprising, but it makes me very cranky about the health of the web platform.

[lgarron]

I've submitted a Firefox bug at https://bugzilla.mozilla.org/show_bug.cgi?id=1810851

[lgarron]

1. Make PublicKeyCredentialWithClientExtensionResults extend Omit<PublicKeyCredential, "authenticatorAttachment"> instead of PublicKeyCredential.

I'm going to go with this option, because this is consistent with the schema, and I can't change the schema without changing Firefox:

https://github.com/github/webauthn-json/blob/80ffb1c7de3bd2fb02a7834fd65c670036f21d1d/src/webauthn-json/basic/schema.ts#L59