RESOLVED / Lessons Learned

1. I can't assume that the log error message is the actual issue. A Heroku error may be a symptom rather than the actual issue.<br>

2. Installation of the Heroku builds-plugin ought to be routine.<br>

3. Thank you to Scott Chacon for Pro Git (online, for free). It's a lifesaver.<br>

4. A shoutout and thank you for this SO 44822146 @https://stackoverflow.com/users/1927832/suresh-atta and to @https://stackoverflow.com/users/3486743/vmarquet for this command: git push heroku main:main --no-verify <br>

5. Finally, since it's buried in the Heroku documentation, here's a link to discussion of the conflict between package-lock.json and yarn.lock (where my troubles began): https://help.heroku.com/0KU2EM53/why-is-my-node-js-build-failing-because-of-conflicting-lock-files