Latitude and longitude

[Transistor]

coordinates = self.props.values()

The property shown in the Property Editor is value, not values. Try,
coordinates = self.props.value

That will return a dictionary, not a list, so you will need to refer to the elements using the key (and we can do it directly without introducing the coordinates variable):
lat = self.props.value.lat
lng = self.props.value.lng

Tips:

1. Use the Script Editor's Browse Properties button to pick properties. It can eliminate this type of error.
2. Post code as code, not as quotations. See below.

Wiki - how to post code on this forum

This thread is intended as a short help file for all those struggling to post formatted code on the forum. Posting formatted code on the forum (and most others) is as simple as selecting the code and pressing the </> button. It works the same as applying Bold or Italic styles to your document. It preserves indentation and applies syntax highlighting. [How to post code]