Fix: Multiple FlutterError.onError calls in FlutterErrorIntegration

[denrase]

📜 Description

Hold the a static reference to the default FlutterError.onError in FlutterErrorIntegration and restore it in integrations close() method.

💡 Motivation and Context

When doing multiple close/init on the SDK, multiple FlutterErrorIntegration instances are instantiated during application lifetime. Every one of them would replace FlutterError.onError function and reference the previous one. This resulted in a chain of calls, where errors were reported multiple times.

💚 How did you test it?

📝 Checklist

• I reviewed submitted code
• I added tests to verify changes
• I updated the docs if needed
• All tests passing
• No breaking changes

🔮 Next steps

[denrase]

Relates to getsentry/sentry-mobile-release-health-app#155 and getsentry/sentry-mobile-release-health-app#161 (comment)

[denrase]

@marandaneto @bruno-garcia Thanks for the detailed feedback, i incorporated the feedback and added one additional test. Should we also change something based on the noop suggestion from @bruno-garcia?

[bruno-garcia]

LGTM

[marandaneto]

@denrase looks like pod-lint is complaining out of the blue, but also on main, could you have a look please?

[marandaneto]

left a note about testing but other than that, LGTM.
thanks for fixing this.

[denrase]

Ok, so apparently with Flutter >= 2.0.0, the Flutter/Flutter.xcframework contains slices for ios-x86_64-simulator and 'ios-armv7_arm64. So when setting x86_64 for the sim valid archs, it fails, as it is not part of the xcframework.

# Flutter.framework does not contain a i386 slice. Only x86_64 simulators are supported.
s.pod_target_xcconfig = { 'DEFINES_MODULE' => 'YES', 'VALID_ARCHS[sdk=iphonesimulator*]' => 'x86_64' }

• When setting the flutter version to '1.22.4', it works as before.
• When chaning to VALID_ARCHS[sdk=iphonesimulator*]' => 'ios-x86_64-simulator', the lint works, but we get the following warning:

- NOTE  | [iOS] xcodebuild:  warning: [CP] Unable to find matching .xcframework slice in 'Flutter/Flutter.xcframework Flutter framework ios-x86_64-simulator ios-armv7_arm64' for the current build architectures (arm64 x86_64 i386).

I'm not sure if we can ignore this warning, or if users will now run into issues when running on simulator. Do you have any suggestions @marandaneto? Think we should do this in a separate issue?