Add tests for Project Euler Problem 5 + minor refactor

[pomkarnath98]

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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 their comments that points to Wikipedia or another similar explanation.
• If this pull request resolves one or more open issues then the commit message contains Fixes: #{$ISSUE_NO}.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 84.76%. Comparing base (5b17ea1) to head (f3afdbb).
Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1691      +/-   ##
==========================================
+ Coverage   84.65%   84.76%   +0.10%     
==========================================
  Files         378      378              
  Lines       19744    19742       -2     
  Branches     2952     2956       +4     
==========================================
+ Hits        16715    16735      +20     
+ Misses       3029     3007      -22     

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[pomkarnath98]

@raklaptudirm @appgurueu I have formatted the code with Prettier. But the Codecov report says, 2 lines in your changes missing coverage. What are we following now to avoid this?

[appgurueu]

As the codecov report shows, the trivial error check is not tested (see https://app.codecov.io/gh/TheAlgorithms/JavaScript/pull/1691/blob/Project-Euler/Problem005.js). I would probably just remove it.

[pomkarnath98]

@appgurueu @raklaptudirm I think this PR now can be reviewed and merged.