Regression: Menu item doesn't save (TypeError: Cannot assign to read only property 'message' of ) in chrome

Steps to reproduce the problem:
1. Open the browser Google Chrome: latest stable version (39.0.2171.71 for me)
2. Goto the channel manager and edit the channel 'English Website'
3. Klik on the edit menu button
4. Select the menu item 'About' (this step is important because the error message only occurs when you selected a new menu item)
5. Change the Internal link from 'about' to 'abouttest'
6. Select the 'label' field so the menu item get saved (on blur event)
7. In the browser console you get the following error
"TypeError: Cannot assign to read only property 'message' of" and the menu item is not saved

Expected Output:
Menu item is saved on a blur event

Actual Output:
Menu item is not saved on a blur event