output: #fixed code
                                  private boolean internalRemove(T element) {
          boolean success = false;
          if (element != null) {
              success = nest.cat(JOhmUtils.getId(owner)).cat(field.getName())
                      .srem(JOhmUtils.getId(element).toString()) > 0;
              unindexValue(element);
          }
          return success;
      }
input: #vulnerable code 
                                  private boolean internalRemove(T element) {
          boolean success = nest.cat(JOhmUtils.getId(owner)).cat(field.getName())
                  .srem(JOhmUtils.getId(element).toString()) > 0;
          unindexValue(element);
          return success;
      } 
                              #location 3 
                              #vulnerability type NULL_DEREFERENCE