Changing model for the view crashes the qml-application

There is three models. First model varModel contains variables. Second paramModel1 and third paramModel2 model contains mapping between parameters and variables from first model.

The top of the window (see attached project) contains TableView of the varModel model (varName-varValue columns).
Below view is situated green button, that adds variables to varModel model using append method.
Below green button is situated yellow button, that choose which model (paramModel1 or paramModel2) is displayed in the ListView at the bottom of the window.

After application starts the bottom view displays paramModel1.
Steps to reproduce the bug:
1. Click on yellow button. The bottom view will display paramModel2;
2. Click on green button. Application will crash.