[MM-58020] Improve error message of NotFound errors in store (#26870)

* Improve error message of NotFound errors in store

* update mmctl tests

server/channels/store/errors.go

@@ -120,10 +120,10 @@ func (e *ErrNotFound) Wrap(err error) *ErrNotFound {
 
 func (e *ErrNotFound) Error() string {
 	if e.wrapped != nil {
-		return fmt.Sprintf("resource: %s id: %s error: %s", e.resource, e.ID, e.wrapped)
+		return fmt.Sprintf("resource %q not found, id: %s, error: %s", e.resource, e.ID, e.wrapped)
 	}
 
-	return fmt.Sprintf("resource: %s id: %s", e.resource, e.ID)
+	return fmt.Sprintf("resource %q not found, id: %s", e.resource, e.ID)
 }
 
 // IsErrNotFound allows easy type assertion without adding store as a dependency.

server/channels/store/errors_test.go

@@ -0,0 +1,28 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package store
+
+import (
+	"errors"
+	"testing"
+
+	"github.com/mattermost/mattermost/server/public/model"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestErrNotFound(t *testing.T) {
+	id := model.NewId()
+
+	t.Run("plain", func(t *testing.T) {
+		err := NewErrNotFound("channel", id)
+
+		assert.EqualError(t, err, "resource \"channel\" not found, id: "+id)
+	})
+	t.Run("with wrapped error", func(t *testing.T) {
+		err := NewErrNotFound("channel", id)
+		err = err.Wrap(errors.New("some error"))
+
+		assert.EqualError(t, err, "resource \"channel\" not found, id: "+id+", error: some error")
+	})
+}