Fixed QML errors preventing the widget to be displayed properly (if at all)

[Iridias]

On recent versions of QT/Plasma (and at least on my system), the widget would not display anything, and spam the log with error-messages such like:

TypeError: Value is null and could not be converted to an object

or

Property value set multiple times

or

Error: Cannot assign [undefined] to QString

This PR solves that.