[local_auth]Fix lock out alert message iOS

[Severancedev]

Description
Fixed an issue with an alertMessage crashing the application after failing to authenticate with fingerprint 5 times (3 + 2) on iOS

Related Issues
Fixes:
flutter/flutter#57129
flutter/flutter#48140

Checklist

Before you create this PR confirm that it meets all requirements listed below by checking the relevant checkboxes ([x]). This will ensure a smooth and quick review process.

• I read the Contributor Guide and followed the process outlined there for submitting PRs.
• My PR includes unit or integration tests for all changed/updated/fixed behaviors (See Contributor Guide).
• All existing and new tests are passing.
• I updated/added relevant documentation (doc comments with ///).
• The analyzer (flutter analyze) does not report any problems on my PR.
• I read and followed the Flutter Style Guide.
• The title of the PR starts with the name of the plugin surrounded by square brackets, e.g. [shared_preferences]
• I updated pubspec.yaml with an appropriate new version according to the pub versioning philosophy.
• I updated CHANGELOG.md to add a description of the change.
• I signed the CLA.
• I am willing to follow-up on review comments in a timely manner.

Breaking Change

Does your PR require plugin users to manually update their apps to accommodate your change?

• Yes, this is a breaking change (please indicate a breaking change in CHANGELOG.md and increment major revision).
• No, this is not a breaking change.

[ajviera]

Can anyone approve this PR? It is super necessary since the error is 100% replicable

[Severancedev]

Format is failing. I can't seem to install the formatting tools. Someone pick it up and format it?

[ShvetsDima]

Same for me, can't install the formatting tools.
May anybody check it please ?

[trunghieuvn]

i have sam as issue,
please merger this PR
thanks

[TMSantos]

Please put some urgency into this PR, its reproducible

[silverhsu1120]

I have same issue.
Any update?

[HungryBytesApps]

Any updates on this? The app still crashes after the 5th attempt. I'm trying to use this on iOS 14.2.

[yaizudamashii]

When will this PR be merged!??? Touch ID on iOS is definitely crashing.

[HungryBytesApps]

Any updates on this?

[stuartmorgan-g]

Thanks for the submission! We apologize for the long delay in triaging this PR. We’re in the process of overhauling our PR triage system to respond much more quickly, as well as working through the backlog.

The underlying issue here is that evaluatePolicy:localizedReason:reply:'s callback can be called on any thread; this PR one specific bug related to that, but there's other code—notably the replies to the Flutter engine—in that codepath that should also be done on the main thread, so the dispatch needs to be moved up a level.

@severance88 Are you still interested in working on this? If so, you can adjust it as described above. If not, I can take over this PR to make the necessary changes (and look into adding a test).

[stuartmorgan-g]

The fix ended up being more involved as other methods were impacted, and there was additional refactoring for testability, so I ended up making a new PR. Closing in favor of #3778.

Thanks again for the initial pass at a fix!