fix: fixed error in the MaxProductOfThree algorithm

[Xolvez]

Fixed the error in the MaxProductOfThree by initializing the max and min variables to null instead of -1. The checks were then altered to check for null instead of -1.

Also wrote more tests, which randomly generated small arrays and compared the output of the maxProductOfThree-algorithm to the output of a slower, but complete, function which calculates all posible triple-products of the values of the array.

Fixes: #1294

 know more

Describe your change:

• Add an algorithm?
• Fix a bug or typo in an existing algorithm?
• Documentation change?

Checklist:

• I have read CONTRIBUTING.md.
• This pull request is all my own work -- I have not plagiarized.
• I know that pull requests will not be merged if they fail the automated tests.
• This PR only changes one algorithm file. To ease review, please open separate PRs for separate algorithms.
• All new JavaScript files are placed inside an existing directory.
• All filenames should use the UpperCamelCase (PascalCase) style. There should be no spaces in filenames.
  Example:UserProfile.js is allowed but userprofile.js,Userprofile.js,user-Profile.js,userProfile.js are not
• All new algorithms have a URL in its comments that points to Wikipedia or other similar explanation.
• If this pull request resolves one or more open issues then the commit message contains Fixes: #{$ISSUE_NO}.

[appgurueu]

Clean fix, clean fuzzing. Thank you for your contribution.