add error handler middleware

internal/web/router.go

@@ -4,17 +4,23 @@ import (
 	"net/http"
 
 	"github.com/flavioribeiro/donut/internal/web/handlers"
+	"go.uber.org/zap"
 )
 
+type ErrorHTTPHandler interface {
+	ServeHTTP(w http.ResponseWriter, r *http.Request) error
+}
+
 func NewServeMux(
 	index *handlers.IndexHandler,
 	signaling *handlers.SignalingHandler,
+	l *zap.Logger,
 ) *http.ServeMux {
 
 	mux := http.NewServeMux()
 
 	mux.Handle("/", index)
-	mux.Handle("/doSignaling", setCors(signaling))
+	mux.Handle("/doSignaling", setCors(errorHandler(l, signaling)))
 	mux.Handle("/demo", http.FileServer(http.Dir("./demo")))
 
 	return mux
@@ -32,3 +38,13 @@ func setCors(next http.Handler) http.Handler {
 		next.ServeHTTP(w, r)
 	})
 }
+
+func errorHandler(l *zap.Logger, next ErrorHTTPHandler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		err := next.ServeHTTP(w, r)
+		if err != nil {
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+			return
+		}
+	})
+}