Unknown crash when selecting puzzle

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One reviewer reports a crash when selecting any puzzle from the main screen. Their Windows version is 10.0.19042.

The Microsoft partner dashboard reports an increase in the number of crashes in the latest build, but cannot display a cause or a stack trace.

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Another reviewer reports that autosave no longer works. This could also be caused by a crash occurring just when the app is being closed.

I'm moving all autosave related code to C#, in the hope that it will actually create a stack trace if it crashes again...

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Changing the exception handling re: autosaves has lowered the total amount of crashes, but didn't fix the original reviewer's problem.