Initial value of custom property of type double is ""

Steps to reproduce:

• Add e.g. Rectangle to Navigator
• In Properties view - Local Custom Properties, click +
• Select Type: double and click "Add property"
• Properties view UI shows value to be 0,00 but code view shows value as "" (property double newName: "")
• Project won't run, error: "Warning: file:///C:/Users/taremes/Documents/UntitledProject52/UntitledProject52Content/Screen01.ui.qml:69:34: Invalid property assignment: number expected