fix(firebase_ui_auth): Catch sms code validation

[wer-mathurin]

Description

This allow the user to pass an onError function when an error happen when validating the sms code

Related Issues

#481

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[wer-mathurin]

@russellwheatley
just a working example of what need to be accomplish.

But the way I've done it may need refactoring. Affecting a completer more than once does not smell well...
Since I'm not familiar with this package, Who can help me with this?

This is a breaking change since the Completer must return a nullable value.

[github-actions]

Hello 👋, this PR has been opened for more than 2 months with no activity on it.

If you think this is a mistake please comment and ping a maintainer to get this merged ASAP! Thanks for contributing!

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[wer-mathurin]

@russellwheatley: Just ping to make sure this is not automagically close

[github-actions]

Hello 👋, this PR has been opened for more than 2 months with no activity on it.

If you think this is a mistake please comment and ping a maintainer to get this merged ASAP! Thanks for contributing!

You have 15 days until this gets closed automatically

[github-actions]

Hello 👋, this PR has been opened for more than 2 months with no activity on it.

If you think this is a mistake please comment and ping a maintainer to get this merged ASAP! Thanks for contributing!

You have 15 days until this gets closed automatically