diff --git a/todo/list.go b/todo/list.go
index 80ba9d2..c45b3dc 100644
--- a/todo/list.go
+++ b/todo/list.go
@@ -1,10 +1,14 @@
 package todo
 
-import (
-	"errors"
-)
+type UserError struct {
+	message string
+}
+
+var ErrorBadId = &UserError{"bad todoItemId"}
 
-var ErrorBadId = errors.New("bad todoItemId")
+func (ue *UserError) Error() string {
+	return ue.message
+}
 
 type Item struct {
 	Title       string
diff --git a/web/handlers.go b/web/handlers.go
index 151f5a8..2e0ab10 100644
--- a/web/handlers.go
+++ b/web/handlers.go
@@ -1,7 +1,6 @@
 package web
 
 import (
-	"errors"
 	"github.com/xpmatteo/todomvc-golang/todo"
 	"html/template"
 	"log"
@@ -53,12 +52,8 @@ func NewItemHandler(templ *template.Template, repository Repository) http.Handle
 			model.Add(title, nil)
 			return nil
 		})
-		if errors.Is(err, todo.ErrorBadId) {
-			badRequest(w, err)
-			return
-		}
 		if err != nil {
-			internalServerError(w, err)
+			handleError(w, err)
 			return
 		}
 
@@ -83,12 +78,8 @@ func ToggleHandler(templ *template.Template, repository Repository) http.Handler
 		model, err := with(repository, func(model *todo.List) error {
 			return model.Toggle(id)
 		})
-		if errors.Is(err, todo.ErrorBadId) {
-			badRequest(w, err)
-			return
-		}
 		if err != nil {
-			internalServerError(w, err)
+			handleError(w, err)
 			return
 		}
 		vm := viewModel(model, r)
@@ -96,6 +87,16 @@ func ToggleHandler(templ *template.Template, repository Repository) http.Handler
 	})
 }
 
+//goland:noinspection GoTypeAssertionOnErrors
+func handleError(w http.ResponseWriter, err error) {
+	switch err.(type) {
+	case *todo.UserError:
+		badRequest(w, err)
+	default:
+		internalServerError(w, err)
+	}
+}
+
 func EditHandler(templ *template.Template, repository Repository) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		err := r.ParseForm()
@@ -113,12 +114,8 @@ func EditHandler(templ *template.Template, repository Repository) http.Handler {
 		model, err := with(repository, func(model *todo.List) error {
 			return model.Edit(id, title)
 		})
-		if errors.Is(err, todo.ErrorBadId) {
-			badRequest(w, err)
-			return
-		}
 		if err != nil {
-			internalServerError(w, err)
+			handleError(w, err)
 			return
 		}
 
@@ -144,7 +141,7 @@ func DestroyHandler(templ *template.Template, repository Repository) http.Handle
 			return model.Destroy(id)
 		})
 		if err != nil {
-			internalServerError(w, err)
+			handleError(w, err)
 			return
 		}