Oracle Error Message
PLS-00565: string must be completed as a potential REF target (object type)
Reason for the Error
Incomplete library units that are potential targets of REF dependencies must be completed so that they continue to remain potential targets of REF dependencies (since there might be library units with REF dependencies on this library unit). Potential REF targets include complete and incomplete object types. This error happened because an attempt was made to complete a potential REF target as something other than a potential REF target.
Solution
Use another name for this library unit, or drop the original incomplete library unit.