Desktop.qml tries to set a value to a null property and read properties from null values
mainDelegate.containment is a null value but it tries to set a variable to a property of it (which of course doesn't exist), causing TypeError: Value is null and could not be converted to an object.
Invalid write to global property "contentX" caused by this line
root.containment is a null value but it tries to read the property availableScreenRect from it