Mandatory default value when adding properties to existing powertags

[jmbenedetto]

Hello.

When I create a powertag, I can define properties leaving the default value empty. However, when I try to do the same by adding new properties to existing powertags, the property is not created if I don't fill the default value field. I fill the property name, click the "Add new property" button and nothing happens. If I input anything at the default value and click the button, the property is added.