TestProgressWeb_KoboIntegration 500s'd on every markup with a
last-read-place bookmark: the panic-recovered stack was a nil pointer
dereference in LibraryService.ResolveMediaPath (s.db deref), reached
from KoboHandler.convertKoboCFIToStandard during kepub CFI conversion.
Two-layer bug:
1. Test harness (root cause): the router.Config built in
test_helpers_test.go omitted LibraryService, so router/sync.go's
SetLibraryService(cfg.LibraryService) stored a nil
*services.LibraryService in the interface field. Production wiring
(main.go:246) was always correct.
2. Latent trap (hardening): `h.libraryService != nil` at the
convertKoboCFIToStandard call site can never catch a typed nil —
an interface holding a nil *LibraryService is non-nil. ResolveMediaPath
now degrades with a "library service not configured" error instead
of panicking on a nil receiver; callers already handle the error
by skipping CFI conversion.
Harness-only fix, zero production behavior change: the endpoint now
returns a clean 200 with the position saved wherever kepub conversion
is unavailable instead of a panic-recovered 500.
Verified: TestProgressWeb_KoboIntegration passes all three subtests
(401 unauthenticated, ReadingSync→last-read-place percentage
preservation, last-read-place without prior ReadingSync) and on
immediate rerun — previously it failed every run.
John O'Keefe
208fc2c4d6