Return every error as {"error": "..."}

Echo errors, middleware and handlers used three different formats (message object, error object, bare string). One error handler now writes all of them the same way; status codes are unchanged.

internal/server/errors.go

@@ -0,0 +1,47 @@
+package server
+
+import (
+	"errors"
+	"net/http"
+
+	"music-server/internal/logging"
+
+	"github.com/labstack/echo/v5"
+	"go.uber.org/zap"
+)
+
+// ErrorResponse is the body of every error response.
+type ErrorResponse struct {
+	Error string `json:"error" example:"Not Found"`
+}
+
+// httpErrorHandler writes every error as an ErrorResponse.
+func httpErrorHandler(c *echo.Context, err error) {
+	if r, _ := echo.UnwrapResponse(c.Response()); r != nil && r.Committed {
+		return
+	}
+
+	code := http.StatusInternalServerError
+	message := http.StatusText(code)
+	var he *echo.HTTPError
+	var sc echo.HTTPStatusCoder
+	switch {
+	case errors.As(err, &he):
+		code = he.Code
+		message = he.Message
+	case errors.As(err, &sc):
+		code = sc.StatusCode()
+	}
+	if code >= http.StatusInternalServerError && he == nil {
+		logging.GetLogger().Error("Unhandled error", zap.String("path", c.Request().URL.Path), zap.Error(err))
+	}
+	if message == "" {
+		message = http.StatusText(code)
+	}
+
+	if c.Request().Method == http.MethodHead {
+		_ = c.NoContent(code)
+		return
+	}
+	_ = c.JSON(code, ErrorResponse{Error: message})
+}

internal/server/middleware/rate_limit.go

@@ -23,9 +23,7 @@ func RateLimit(limit int, window time.Duration) echo.MiddlewareFunc {
 		logging.GetLogger().Warn("Rate limit exceeded",
 			zap.String("ip", identifier),
 			zap.String("path", c.Request().URL.Path))
-		return c.JSON(http.StatusTooManyRequests, map[string]string{
-			"error": "Rate limit exceeded. Please try again later.",
-		})
+		return echo.NewHTTPError(http.StatusTooManyRequests, "Rate limit exceeded. Please try again later.")
 	}
 	return echoMiddleware.RateLimiterWithConfig(config)
 }

internal/server/middleware/sync_check.go

@@ -14,7 +14,7 @@ func SyncCheck(isSyncing func() bool) echo.MiddlewareFunc {
 		return func(c *echo.Context) error {
 			if isSyncing() {
 				logging.GetLogger().Info("Syncing is in progress - request blocked")
-				return c.JSON(http.StatusLocked, "Syncing is in progress")
+				return echo.NewHTTPError(http.StatusLocked, "Syncing is in progress")
 			}
 			return next(c)
 		}

internal/server/middleware/token_auth.go

@@ -28,11 +28,11 @@ func TokenAuth(q repository.Querier, disabled bool) echo.MiddlewareFunc {
 			}
 
 			if c.Request().Header.Get("Authorization") == "" {
-				return c.JSON(http.StatusUnauthorized, map[string]string{"error": "Authorization header required"})
+				return echo.NewHTTPError(http.StatusUnauthorized, "Authorization header required")
 			}
 			token, ok := BearerToken(c)
 			if !ok {
-				return c.JSON(http.StatusUnauthorized, map[string]string{"error": "Invalid authorization format. Use: Bearer <token>"})
+				return echo.NewHTTPError(http.StatusUnauthorized, "Invalid authorization format. Use: Bearer <token>")
 			}
 
 			ctx := c.Request().Context()
@@ -42,7 +42,7 @@ func TokenAuth(q repository.Querier, disabled bool) echo.MiddlewareFunc {
 					zap.String("ip", c.RealIP()),
 					zap.String("error", err.Error()),
 				)
-				return c.JSON(http.StatusUnauthorized, map[string]string{"error": "Invalid or expired token"})
+				return echo.NewHTTPError(http.StatusUnauthorized, "Invalid or expired token")
 			}
 
 			if time.Now().After(session.ExpiresAt.Time) {
@@ -52,7 +52,7 @@ func TokenAuth(q repository.Querier, disabled bool) echo.MiddlewareFunc {
 						logging.GetLogger().Error("Failed to delete expired session", zap.Error(err))
 					}
 				}(context.WithoutCancel(ctx))
-				return c.JSON(http.StatusUnauthorized, map[string]string{"error": "Token expired"})
+				return echo.NewHTTPError(http.StatusUnauthorized, "Token expired")
 			}
 
 			c.Set("session", session)

internal/server/music_handler.go

@@ -34,7 +34,7 @@ func NewMusicHandler(music *backend.MusicService) *MusicHandler {
 func (m *MusicHandler) GetSong(ctx *echo.Context) error {
 	song, err := strconv.Atoi(ctx.QueryParam("song"))
 	if err != nil {
-		return ctx.String(http.StatusBadRequest, "song must be a number")
+		return echo.NewHTTPError(http.StatusBadRequest, "song must be a number")
 	}
 	path, err := m.music.Song(song)
 	return serveSong(ctx, path, err)
@@ -204,7 +204,7 @@ func (m *MusicHandler) GetAllSoundtracksRandom(ctx *echo.Context) error {
 func (m *MusicHandler) PutPlayed(ctx *echo.Context) error {
 	song, err := strconv.Atoi(ctx.QueryParam("song"))
 	if err != nil {
-		return ctx.JSON(http.StatusBadRequest, err.Error())
+		return echo.NewHTTPError(http.StatusBadRequest, "song must be a number")
 	}
 	logging.GetLogger().Info("Marking song as played", zap.Int("song_id", song))
 	if err := m.music.SetPlayed(ctx.Request().Context(), song); err != nil {

internal/server/routes.go

@@ -59,6 +59,7 @@ func (s *Server) handlers() handlers {
 
 func (s *Server) RegisterRoutes() http.Handler {
 	e := echo.New()
+	e.HTTPErrorHandler = httpErrorHandler
 	if len(s.cfg.TrustedProxies) > 0 {
 		var trust []echo.TrustOption
 		for _, ipNet := range s.cfg.TrustedProxies {

internal/server/statistics_handler.go

@@ -43,7 +43,7 @@ func parseLimit(ctx *echo.Context) (int32, bool) {
 func withLimit[T any](ctx *echo.Context, name string, query func(*echo.Context, int32) (T, error)) error {
 	limit, ok := parseLimit(ctx)
 	if !ok {
-		return ctx.JSON(http.StatusBadRequest, map[string]string{"error": "Invalid limit parameter"})
+		return echo.NewHTTPError(http.StatusBadRequest, "Invalid limit parameter")
 	}
 	result, err := query(ctx, limit)
 	return statsResult(ctx, name, result, err)
@@ -52,7 +52,7 @@ func withLimit[T any](ctx *echo.Context, name string, query func(*echo.Context,
 func statsResult[T any](ctx *echo.Context, name string, result T, err error) error {
 	if err != nil {
 		logging.GetLogger().Error("Failed to get statistics", zap.String("statistic", name), zap.Error(err))
-		return ctx.JSON(http.StatusInternalServerError, map[string]string{"error": "Failed to get statistics"})
+		return echo.NewHTTPError(http.StatusInternalServerError, "Failed to get statistics")
 	}
 	return ctx.JSON(http.StatusOK, result)
 }

internal/server/sync_handler.go

@@ -57,7 +57,7 @@ func (s *SyncHandler) SyncSoundtracksNewFull(ctx *echo.Context) error {
 
 func (s *SyncHandler) start(ctx *echo.Context, full bool, message string) error {
 	if !s.sync.Start(full) {
-		return ctx.JSON(http.StatusLocked, "Syncing is in progress")
+		return echo.NewHTTPError(http.StatusLocked, "Syncing is in progress")
 	}
 	logging.GetLogger().Info(message)
 	return ctx.JSON(http.StatusOK, message)

internal/server/token_handler.go

@@ -75,14 +75,14 @@ func (h *TokenHandler) passwordValid(password string) bool {
 func (h *TokenHandler) CreateTokenHandler(c *echo.Context) error {
 	var req TokenRequest
 	if err := c.Bind(&req); err != nil {
-		return c.JSON(http.StatusBadRequest, map[string]string{"error": "Invalid request body"})
+		return echo.NewHTTPError(http.StatusBadRequest, "Invalid request body")
 	}
 
 	if !h.passwordValid(req.Password) {
 		logging.GetLogger().Warn("Invalid password attempt for token creation",
 			zap.String("ip", c.RealIP()),
 			zap.String("user_agent", c.Request().UserAgent()))
-		return c.JSON(http.StatusUnauthorized, map[string]string{"error": "Invalid password"})
+		return echo.NewHTTPError(http.StatusUnauthorized, "Invalid password")
 	}
 
 	if req.ClientType == "" {
@@ -92,7 +92,7 @@ func (h *TokenHandler) CreateTokenHandler(c *echo.Context) error {
 	token, err := generateToken()
 	if err != nil {
 		logging.GetLogger().Error("Failed to generate token", zap.Error(err))
-		return c.JSON(http.StatusInternalServerError, map[string]string{"error": "Failed to generate token"})
+		return echo.NewHTTPError(http.StatusInternalServerError, "Failed to generate token")
 	}
 
 	session, err := h.q.CreateSession(c.Request().Context(), repository.CreateSessionParams{
@@ -104,7 +104,7 @@ func (h *TokenHandler) CreateTokenHandler(c *echo.Context) error {
 	})
 	if err != nil {
 		logging.GetLogger().Error("Failed to create session", zap.Error(err))
-		return c.JSON(http.StatusInternalServerError, map[string]string{"error": "Failed to create session"})
+		return echo.NewHTTPError(http.StatusInternalServerError, "Failed to create session")
 	}
 
 	clientType := req.ClientType
@@ -131,16 +131,16 @@ func (h *TokenHandler) CreateTokenHandler(c *echo.Context) error {
 //	@Router			/api/v1/token [delete]
 func (h *TokenHandler) DeleteTokenHandler(c *echo.Context) error {
 	if c.Request().Header.Get("Authorization") == "" {
-		return c.JSON(http.StatusUnauthorized, map[string]string{"error": "Authorization header required"})
+		return echo.NewHTTPError(http.StatusUnauthorized, "Authorization header required")
 	}
 	token, ok := middleware.BearerToken(c)
 	if !ok {
-		return c.JSON(http.StatusUnauthorized, map[string]string{"error": "Invalid authorization format"})
+		return echo.NewHTTPError(http.StatusUnauthorized, "Invalid authorization format")
 	}
 
 	if err := h.q.DeleteSession(c.Request().Context(), token); err != nil {
 		logging.GetLogger().Error("Failed to delete session", zap.Error(err))
-		return c.JSON(http.StatusInternalServerError, map[string]string{"error": "Failed to invalidate token"})
+		return echo.NewHTTPError(http.StatusInternalServerError, "Failed to invalidate token")
 	}
 	return c.JSON(http.StatusOK, map[string]string{"status": "token invalidated"})
 }
@@ -159,7 +159,7 @@ func (h *TokenHandler) DeleteTokenHandler(c *echo.Context) error {
 func (h *TokenHandler) CleanupExpiredSessionsHandler(c *echo.Context) error {
 	if err := h.q.DeleteExpiredSessions(c.Request().Context()); err != nil {
 		logging.GetLogger().Error("Failed to cleanup sessions", zap.Error(err))
-		return c.JSON(http.StatusInternalServerError, map[string]string{"error": "Failed to cleanup sessions"})
+		return echo.NewHTTPError(http.StatusInternalServerError, "Failed to cleanup sessions")
 	}
 	return c.JSON(http.StatusOK, map[string]string{"status": "cleanup complete"})
 }