Attempting to use current entity but none exists.
          #6049   Run-time catchable error
          Attempting to use current entity but none exists.
Additional Information
 Unqualified external entity accessed outside an 'X' rule.
     where X is either EXTERNAL-TEXT-ENTITY or EXTERNAL-TEXT-ENTITY.
Explanation
This error is issued when a function accesses an unqualified entity,
notation, or data-attribute, but it turns out the function is not
called from an EXTERNAL-TEXT-ENTITY or EXTERNAL-TEXT-ENTITY rule.