fix(formatter): zero triggering fallback return

[seanc]

Proposed changes

This pull request fixes issue #38

When passing zero in formatNumber, it was considered falsey and triggered the fallback return statement resulting in a null return.

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist

• I have read the CONTRIBUTING doc
• Lint and unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works.
• I have added necessary documentation (if appropriate)

[coveralls]

Coverage remained the same at 95.918% when pulling f111616 on seanc:develop into 0b0eff2 on adonisjs:develop.

[RomainLanz]

Thanks! 💜