Invalid operation on a variable-size shelf encountered.

#2044   Compile-time error

Invalid operation on a variable-size shelf encountered.

Additional Information

Trying to insert an item X item M of Y 'Z'.
    or
Trying to insert an item X item M of Y 'Z', maximum size is N.
    where X is 'BEFORE' or 'AFTER', Y is the type of the shelf, Z its name, M the position of insertion, N the maximum size. If N isn't given, the insertion point is too low.