The include shortcode previously called readFile directly, which renders
nothing when the target is missing instead of failing. That let renamed
or deleted snippets linger as silent no-ops (for example the stale
scout-early-access.md and compose/develop.md references).
Check fileExists first and errorf with the shortcode position when the
target is missing, mirroring the file/files shortcodes. Verified against
Hugo 0.163.0: valid includes still render; a missing target now fails the
build with the offending file and line.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>