Added exports.default to package.json

[daleyjem]

Per NodeJS documentation on the package.json exports object, there seems to be a need for a fallback default key:
https://nodejs.org/api/packages.html#conditional-exports

Additionally, I'm seeing things like eslint fail to resolve until a default key has been specified. I've not dug any further into why, but I think some default should be defined until more options should later be added.

[codecov]

Codecov Report

Merging #1630 (ec8de58) into master (8c1dd48) will not change coverage.
The diff coverage is n/a.

❗ Current head ec8de58 differs from pull request most recent head e5617c1. Consider uploading reports for the commit e5617c1 to get more accurate results

@@           Coverage Diff           @@
##           master    #1630   +/-   ##
=======================================
  Coverage   99.60%   99.60%           
=======================================
  Files           5        5           
  Lines         507      507           
  Branches      142      142           
=======================================
  Hits          505      505           
  Misses          2        2           

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[jeremy-daley-kr]

@3imed-jaberi Who has the ability to merge this?