feat: handling null response from navigator.credentials.create

[hcho112]

Pre-flight checklist

• I have read the Contributing Guidelines on pull requests.
• Commit messages follow the conventional commits spec
• If this is a code change: I have written unit tests.
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• If this is a new API or substantial change: the PR has an accompanying issue (closes #0000) and the maintainers have approved on my working plan.

Motivation

This PR contains small change on biometric-ed25519 package where upon creating passkey from the browser, sometimes it is possible that navigator.credentials.create({ publicKey }) code can return null and it breaks the flow without being handled.

There was an issue reported and discussed that reflect the outcome of this PR.

Test Plan

(I have locally imported this change and run account creation flow on fast-auth-signer repo and it shows alert as expected)

Related issues/PRs

issue

[changeset-bot]

🦋 Changeset detected

Latest commit: b3617f9

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@near-js/biometric-ed25519	Minor

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[frol]

@andy-haynes I have just noticed this PR. It looks good to me. Should we merge it?