Update canonical-data.json

[mohamad-shoumar]

Added a check where position of X is not at last position

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[IsaacG]

See existing test 28025280-2c39-4092-9719-f3234b89c627

[MatthijsBlom]

Test 28025280-2c39-4092-9719-f3234b89c627 proved insufficient to catch the solution that inspired this test.

Presently there is no test about candidate codes containing both a valid and an invalid X. The test case proposed here does cover this case, but I'm not sure it is the best one. When I presented it to Mohamad I did not plan on it being included among the canonical test cases.

[IsaacG]

Should we move the discussion to the forum? Changes should be discussed there prior to opening PRs.

[MatthijsBlom]

I was not planning on championing this proposal, and will not participate in a forum discussion, sorry.

I'm just dropping by here to clear up a confusion that landed in my GH notifications feed.

The only thing I might otherwise have wanted to add in the future: a better test case would be, I think, a random candidate number ending in X that is valid, except that it also contains an X in another place (making it invalid). The randomness would be there to signal that nothing special is going on, other than the Xs.