A fresh install ends on a 500 and logs hundreds of errors

Problem/Motivation

A fresh Drupal CMS install with the RightUp site template picked in the installer finishes, then redirects to /admin/dashboard/welcome, which returns HTTP 500. The install also logs about 250 errors. Measured on a clean build:

81  canvas      Twig\Error\LoaderError, vartheme_bs5_rightup:section is not defined
66  php         Undefined array key "target_id" / Undefined array key ""
61  system      ComponentNotFoundException for vartheme_bs5_rightup:section
40  search_api  The theme stark does not exist or is not installed
17  system      block plugin not found

One drush cr clears all of it and the finished site is correct: every page 200, entities load clean, no pending entity schema updates. But that is not what someone doing a browser install sees.

Root cause. The content search index has index_directly: true, so every node the recipe imports is indexed inline, which renders it in the search_index view mode. During the install the active theme is still the one the request started with, stark, which is not installed, because the theme is negotiated once per request and cached, so setting system.theme mid-request does not reach the renderer. The search_api failures are the direct symptom; the Canvas and component errors are the same render path failing on components that are not registered yet.

Steps to reproduce

1. Build a fresh Drupal CMS site and run the browser installer.
2. Pick the RightUp site template at the installer's template step and finish the install.
3. The installer redirects to /admin/dashboard/welcome, which returns HTTP 500.
4. drush watchdog:show --count=500 shows roughly 250 errors in the classes above.

Proposed resolution

Index on cron instead of on save, as a config action on the index the recipe already configures:

search_api.index.content:
  simpleConfigUpdate:
    options.index_directly: false

Nothing renders during the install, so all five error classes go away. Content is indexed on the first cron run.

It has to be merged into the recipe's existing search_api.index.content action, not added as a second one: two actions with the same key silently collapse to one in YAML.

Remaining tasks

• ✅ File an issue
• ❌ Addition/Change/Update/Fix
• ❌ Testing to ensure no regression
• ❌ Verify on a fresh browser install that the welcome dashboard returns 200 and the watchdog is clean
• ❌ Confirm search results still appear after cron
• ➖ Automated unit/functional testing coverage
• ➖ Developer Documentation support
• ➖ User Guide Documentation support
• ➖ UX/UI designer responsibilities
• ➖ Accessibility and Readability
• ❌ Reviewed by a human
• ❌ Code review by maintainers
• ❌ Full testing and approval
• ❌ Credit contributors
• ❌ Review with the product owner
• ❌ Update Release Notes
• ❌ Release

User interface changes

• N/A

API changes

• N/A

Data model changes

• N/A

Release notes snippet

• A fresh install no longer ends on an HTTP 500. The content search index is built on cron instead of during the install.