output: #fixed code
                                  protected LookupResult extractNode(List<LexicalPatternElement> nextElements, TokenDistributor distributor) {
          int skip = 0;
  
          for (LexicalPatternElement nextElement : nextElements) {
              if (!nextElement.isWildcard()) {
                  break;
              }
  
              skip++;
          }
  
          int indexBackup = distributor.getIndex();
  
          for (int i = skip; i < nextElements.size(); i++) {
              LexicalPatternElement element = nextElements.get(i);
              distributor.setIndex(indexBackup);
  
              // consider exclusion of wildcards here
  
              LookupResult result = elementLookupExtractor.extractNode(nextElements.subList(0, skip), element, distributor);
              result.matchedIndex = i;
  
              if (result.getMergedResults().isMatched()) {
                  return result;
              }
  
              if (element.isOptional()) {
                  continue;
              }
  
              break;
          }
  
          return new LookupResult();
      }
input: #vulnerable code 
                                  protected LookupResult extractNode(List<LexicalPatternElement> nextElements, TokenDistributor distributor) {
          int skip = 0;
  
          for (LexicalPatternElement nextElement : nextElements) {
              if (!nextElement.isWildcard()) {
                  break;
              }
  
              skip++;
          }
  
          int indexBackup = distributor.getIndex();
  
          for (int i = skip; i < nextElements.size(); i++) {
              LexicalPatternElement element = nextElements.get(i);
              distributor.setIndex(indexBackup);
  
              LookupResult result = elementLookupExtractor.extractNode(nextElements.subList(0, skip), element, distributor);
              result.matchedIndex = i;
  
              if (result.getMergedResults().isMatched()) {
                  return result;
              }
  
              if (element.isOptional()) {
                  continue;
              }
  
              break;
          }
  
          return new LookupResult();
      } 
                              #location 19 
                              #vulnerability type NULL_DEREFERENCE