#vulnerable code 
                              private void fnStatement() {
    move(true);

    checkVariableName();
    checkFunctionName();
    getCodeGeneratorWithTimes().onConstant(this.lookhead);
    move(true);
    if (!expectChar('(')) {
      reportSyntaxError("expect '(' after function name");
    }
    lambda(true);
    ensureFeatureEnabled(Feature.Assignment);
    getCodeGeneratorWithTimes().onAssignment(currentToken().withMeta(Constants.DEFINE_META, true));
  } 
                            #location 5 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                              private void fnStatement() {
    move(true);

    checkVariableName(this.lookhead);
    checkFunctionName(this.lookhead, true);
    getCodeGeneratorWithTimes().onConstant(this.lookhead);
    move(true);
    if (!expectChar('(')) {
      reportSyntaxError("expect '(' after function name");
    }
    lambda(true);
    ensureFeatureEnabled(Feature.Assignment);
    getCodeGeneratorWithTimes().onAssignment(currentToken().withMeta(Constants.DEFINE_META, true));
  }