The package-root override branch of `resolveCanonicalPiSpecifier` returned
the bunfs override path without checking the target was actually present,
so when `bun --compile` quietly dropped one of the extra entrypoints
(observed on macOS arm64 release binaries), the static rewrite emitted a
`file://` URL to a missing module. The #1216 fallback only fired on the
throwing `getResolvedSpecifier` path, so the override never threw and the
rewrite committed the bad URL — extensions silently failed to load.
Each override target is now checked with `fs.existsSync` at module init.
Missing entries are dropped from `LEGACY_PI_PACKAGE_ROOT_OVERRIDES` so
`resolveCanonicalPiSpecifier` falls through to `getResolvedSpecifier`,
which throws under bunfs and triggers the existing rewrite catch — Bun
then resolves the canonical `@oh-my-pi/pi-*` specifier from the
extension's own `node_modules`.
Fixes#2168
roboomp
4a6362192d