Disable ThrowAssertion for watchOS to make Nimble compile for watchOS

[danielsaidi]

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help you if you're not sure:

• What behavior was changed?
• What code was refactored / updated to support this change?
• What issues are related to this PR? Or why was this change introduced?

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• Does this have tests?
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• Does this break the public API (Requires major version bump)?
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[danielsaidi]

I have had problem with Nimble for a long time, when developing multi-platform libraries for watchOS or watchOS apps. Nimble just won't compile, since the BadInstructionException isn't defined for watchOS.

I made Nimble compile on watchOS by adding an #if switch to throwAssertion, that throws a fatal error for watchOS, much like it already does for other unsupported platforms.

This means that throwAssertion will always fail for watchOS, but at least the code will compile and any developers that use throwAssertion will get a descriptive error and have the choice to disable these tests for watchOS.

I also disabled ThrowAssertionTests for watchOS, and can confirm that the Nimble unit tests run perfectly on watchOS.

There is already another PR for watchOS, but this is much smaller and should be easier to merge. Perhaps we can merge this as a first step, before taking on the other PR that has been waiting since June?

If we merge this PR, then create a new patch version for Nimble and use that in Quick, both libraries will hopefully compile for and support watchOS, with the only small caveat that throwAssertion currently doesn't work as expected on watchOS.

[younata]

Hey @danielsaidi, this makes sense. I updated your branch with latest main.

[danielsaidi]

Hey @younata - thank you! I'm looking forward to a new release with this fix :)