Make sure public/script/ files exist

[imnasnainaec]

Fixes #843
Prequel to #3041

Building with CRA and a script file missing just has a console error. But the missing file causes a Parcel build to fail.

---

This change is 

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 74.30%. Comparing base (7218d23) to head (c860c93).
⚠️ Report is 43 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #3960   +/-   ##
=======================================
  Coverage   74.30%   74.30%           
=======================================
  Files         292      292           
  Lines       10794    10794           
  Branches     1352     1352           
=======================================
  Hits         8021     8021           
  Misses       2387     2387           
  Partials      386      386           

Flag	Coverage Δ
backend	85.45% <ø> (ø)
frontend	65.70% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[jasonleenaylor]

@jasonleenaylor reviewed 4 of 4 files at r1, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @imnasnainaec)