Improve error message for email/password sign-in on OAuth accounts

[ashishyk018-byte]

Fixes #1313

Improves the error message shown when Email/Password sign-in is attempted
for accounts originally created via OAuth, without relying on deprecated
auth APIs.

Manually verified the updated error handling logic.

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[ashishyk018-byte]

Thanks! Happy to make any changes if needed 🙂

[russellwheatley]

Hi @ashishyk018-byte - Thank you for the PR. We haven't made a decision on the best approach to this particular issue at this moment in time, but I'll let you know when a decision has been made 🙏

[ashishyk018-byte]

Thanks for the update! 👍
Happy to adjust the approach or make changes once a direction is decided.

[ashishyk018-byte]

The relevant change for this PR is the commit Clear form validation errors when input is corrected

[MichaelVerdon]

Hi there, after some experimenting we won't be able to accept this PR as the only way we can catch out by provider is using the fetchSignInMethodsForEmail(); method and checking against that which also requires email enumeration protection disabled which is generally not recommended. Errors were likely naturally kept vague to prevent bad actors from finding out why sign in failed but instead we will add to the react example app on how it can be done for those who want it in their application. Proposed solution would overwrite other errors.

[ashishyk018-byte]

Thanks for looking into this and for the detailed explanation.

That makes sense regarding email enumeration protection and keeping errors intentionally vague for security reasons. I understand why this shouldn't be part of the core library.

I appreciate the clarification and the plan to demonstrate it in the React example app instead. Thanks again for reviewing and experimenting with the approach.