refactor(server): final writeErr migration + ErrNotFound aliases (T3c)

internal/tracks/service.go

@@ -25,13 +25,16 @@ import (
 	"github.com/jackc/pgx/v5/pgtype"
 	"github.com/jackc/pgx/v5/pgxpool"
 
+	"git.fabledsword.com/bvandeusen/minstrel/internal/apierror"
 	"git.fabledsword.com/bvandeusen/minstrel/internal/coverart"
 	"git.fabledsword.com/bvandeusen/minstrel/internal/db/dbq"
 )
 
-// ErrNotFound is returned when the track id doesn't resolve. Handler
-// maps to 404 `not_found`.
-var ErrNotFound = errors.New("tracks: not found")
+// ErrNotFound is returned when the track id doesn't resolve. Aliased
+// to apierror.ErrNotFound so handlers can errors.Is against the shared
+// sentinel; existing tracks.ErrNotFound callsites still resolve to the
+// same pointer.
+var ErrNotFound = apierror.ErrNotFound
 
 // LidarrUnmonitorer is the subset of *lidarr.Client RemoveTrack uses.
 // Defined as an interface so tests can stub without spinning up a Lidarr