fix panic when using unhashable types

[seminmw]

This fix #369

[seminmw]

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[seminmw]

@richardpark-msft @richardpark-msft @RickWinter

Could you please take a look at my pull request when you have a moment? I'd appreciate your feedback and suggestions.

Thanks in advance!

[seminmw]

@richardpark-msft @richardpark-msft @RickWinter
Can you see my PR?