If you get this error when building for iOS:
LocationService class is used but Locations Usage Description is empty.
This happens because Playmaker ships with LocationService actions by default.
If you are not using any Location actions, you can delete these actions in Assets\PlayMaker\Actions\Device:
GetLocationInfo.cs
ProjectLocationToMap.cs
StartLocationServiceUpdates.cs
StopLocationServiceUpdates.cs
If you are using any of these actions, then you need to add a Location Usage Description in PlayerSettings as required by Apple.