Fixed "Cannot read properties of undefined (reading 'update')" errors
caused by chart setTimeout callbacks persisting across Turbolinks page
navigations.
Changes:
- Add existence checks before initializing charts
- Guard all .update() calls with element and instance checks
- Track all setTimeout IDs in chartTimeouts array
- Clear timeouts on Turbolinks navigation events
- Clear timeouts at start of pieChartHome() to prevent duplicates
This ensures chart update callbacks only run when chart elements exist
on the page, preventing errors when navigating to pages without charts.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude <noreply@anthropic.com>
* add 'aria-label' into some elements without the label
* add 'aris-label' into some visual elements
* replace some 'a' elements have a button action to 'button'
no functional change here, but familiar Rails users will see view files in the
locations they expect. this also slightly simplifies controller code
there is one attendant change in the wiki at `rails_3/A1-SQL-Injection-Interpolation.md`
that I'm happy to make after the PR is merged.
Ken Johnson