Attempting to use an existing referent with no defined value in the current nested-referents scope.
#6087 Run-time catchable error
Attempting to use an existing referent with no defined value in the current nested-referents scope.
Additional Information
For referent 'X'.
where X is the name of the referent.
Explanation
This error occurs when a referent which has never been assigned a
value gets directly or indirectly written to a stream that is resolved
at the end of the referent scope.