fix(nextjs): avoid race condition in oauth callback and route protection

[brionmario]

Purpose

• avoid race condition in oauth callback and route protection
• handle empty payload in sign-in action

Related Issues

• chore: stabilize @asgardeo/react & @asgardeo/nextjs #81

Related PRs

• N/A

Checklist

• Followed the CONTRIBUTING guidelines.
• Manual test round performed and verified.
• Documentation provided. (Add links if there are any)
• Unit tests provided. (Add links if there are any)

Security checks

• Followed secure coding standards in http://wso2.com/technical-reports/wso2-secure-engineering-guidelines?
• Confirmed that this PR doesn't commit any keys, passwords, tokens, usernames, or other secrets?

[asgardeo-github-bot]

🦋 Changeset detected

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

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