The variable $data seems to never exist, and therefore isset should always return false. Did you maybe rename this variable?
This check looks for calls to isset(...) or empty() on variables
that are yet undefined. These calls will always produce the same result and
can be removed.
This is most likely caused by the renaming of a variable or the removal of
a function/method parameter.
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.