The property ID does not seem to exist in SS_Object.
An attempt at access to an undefined property has been detected. This may either be a typographical error
or the property has been renamed but there are still references to its old name.
If you really want to allow access to undefined properties, you can define magic methods
to allow access. See the php core documentation on Overloading.
You can fix this by adding a namespace to your class:
When choosing a vendor namespace, try to pick something that is not too generic to avoid conflicts with other libraries.