[PLAT-2016] Fix Swift fatal error message reporting

[nickdowell]

Goal

Improve the reliability of capturing Swift fatal error messages passed to the following functions:

• assertionFailure()
• fatalError()
• preconditionFailure()

It also covers implicit messages emitted by the Swift standard library, e.g.

Unexpectedly found nil while unwrapping an Optional value

As a bonus, the same mechanism also captures error messages from other libraries such as libdispatch, e.g.

BUG IN CLIENT OF LIBDISPATCH: dispatch_sync called on queue already owned by current thread

Design

The implementation examines the binary image of the crashing thread's top stack frame for a message in its __crash_info section, and parses this to extract the error type and message.

The full, raw value of the __crash_info message is also made available in the event metadata, which may be useful when diagnosing certain types of crash.

Changeset

• Updated KSCrash to capture the __crash_info message and store it in the KSCrashReport.
• Updated BugsnagError and BugsnagEvent to read the message stored in the KSCrashReport, parse it, and update the error & event payload.
• Removed code for old mechanism (RegisterErrorData)
• Disabled KSCrash's memory introspection option.

Testing

• Manually verified with example app using iPhone Simulator and real devices, including 32-bit CPUs.
• Added new unit test case to validate parsing of crash info message.
• Updated E2E scenarios to validate that Swift error messages are reported correctly.
• Added new E2E scenario for libdispatch crash.

[sethfri]

This is so awesome! Thanks for your work on this @nickdowell. Since this covers force unwrapping optionals, do you expect this to also capture the Error thrown from a try!, described in #950?

[nickdowell]

@sethfri I am not sure about the errors thrown from a try! - will be investigating 🤓

[nickdowell]

@sethfri quick update: a description of the Error is included in the message when try! causes a crash 😄 Example:

[github-actions]

Bugsnag.framework binary size

	iOS arm64
Before	1,055,544 bytes
After	1,053,864 bytes
Diff	-1680

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