examples/quick/painteditem prints out errors: TypeError: 'NoneType' object is not callable

Qt for Python example quick/painteditem at least in 6.1.3 prints out the following errors when clicking on the button:

file:///examples/quick/painteditem/main.qml:102:
    TypeError: 'NoneType' object is not callable
file://examples/quick/painteditem/main.qml:65: TypeError: Cannot read property 'right' of null

The first error is repeated a number of times first after which the second one starts appearing as well.

Steps to reproduce the problem:

1. Run the example
2. Click on the "Add another balloon" button repeatedly

cf qtdeclarative/examples/quick/customitems/painteditem