#vulnerable code 
                                void removeEntity(Object entity) {
        Class<?> type = entity.getClass();
        ClassInfo classInfo = metaData.classInfo(type.getName());
        FieldInfo identityReader = classInfo.identityField();
        Long id = (Long) identityReader.readProperty(entity);

        purge(entity, identityReader, type);

        if (id != null) {
            typeRegister.remove(metaData, type, id);
        }
    } 
                            #location 4 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                boolean removeRelationship(MappedRelationship mappedRelationship) {
        return relationshipRegister.remove(mappedRelationship);
    }