Attempting to use a referent that does not exist.
#6086 Run-time catchable error
Attempting to use a referent that does not exist.
Additional Information
For referent 'X'.
where X is the name of the referent.
Explanation
This error occurs when an attempt is made to access a referent using
REFERENTS Key or to display a referent (by writing the
referent to a stream open with with referents-displayed) that
is not defined within the current referents scope (i.e. does not exist
on the referents shelf).