Link to issue number:

No issue filed — minor/trivial CI workflow fix.

Summary of the issue:

Since #20058 (commit 25b57b8), the clearCaches scheduled workflow fails on every fork that does not have the CACHE_EXPIRATION_HOUR repository variable set. The workflow runs every 3 hours and consistently fails with:

Error reading JToken from JsonReader. Path '', line 0, position 0.

This is a regression: before #20058 the expression was inputs.cache_expiration || 6, which worked fine on forks.

Description of user facing changes:

None.

Description of developer facing changes:

The clearCaches scheduled workflow now works on forks out of the box, as described in ci/README.md ("Builds from PRs and pushes to master/beta/rc should work out of the box for forks").

Description of development approach:

#20058 changed the env var expression to:

CACHE_EXPIRATION_HOUR: ${{ inputs.cache_expiration || fromJSON(vars.CACHE_EXPIRATION_HOUR) || 6 }}

When CACHE_EXPIRATION_HOUR is not set as a repository variable, GitHub Actions evaluates vars.CACHE_EXPIRATION_HOUR as an empty string. fromJSON("") throws a hard parse error rather than returning a falsy value, so the intended || 6 fallback is never reached.

Fix: move the default inside fromJSON so the empty string is handled before parsing:

CACHE_EXPIRATION_HOUR: ${{ inputs.cache_expiration || fromJSON(vars.CACHE_EXPIRATION_HOUR || '6') }}

This preserves the existing behaviour for repos that have the variable set, and correctly falls back to 6 hours for forks that do not.

Testing strategy:

Manually triggered the fixed workflow on the bramd/nvda fork (which does not have CACHE_EXPIRATION_HOUR set) — run 26745038474 succeeded in 4 s, compared to consistent failures on the same fork before the fix.

Before the fix, scheduled run 26735057185 failed with the JSON parse error on line 15.

Known issues with pull request:

None.

Code Review Checklist:

• Documentation:
  • Change log entry — not required, no user-facing change
  • User Documentation — N/A
  • Developer / Technical Documentation — N/A (ci/README.md already states this workflow works out of the box for forks)
  • Context sensitive help for GUI changes — N/A
• Testing:
  • Unit tests — N/A (workflow file)
  • System (end to end) tests — N/A
  • Manual testing — manually triggered on a fork without the variable set; passed
• UX of all users considered — N/A (CI workflow only)
• API is compatible with existing add-ons — N/A
• Security precautions taken — N/A