I updated the git version of the project.
Whenever you bind a control through value binding, then it calls its getter method to load the values. whereas when you tries to modify these values, it will try to call the setter method of the property. In the project the dictionaries were hardcoded therefore there were no setter method and that is the reason why you got the "Error setting value for key path objectValue.selected".
Check the new version where the FruitModel has been created which resolves the setter issue.
Let me know if you face any problems.