#vulnerable code 
                              @Override
  public AviatorObject match(AviatorObject other, Map<String, Object> env) {
    switch (other.getAviatorType()) {
      case String:
        AviatorString aviatorString = (AviatorString) other;
        Matcher m = this.pattern.matcher(aviatorString.lexeme);
        if (m.matches()) {
          boolean captureGroups =
              AviatorEvaluator.getOption(Options.CAPTURING_GROUPS_IN_PATTERN_MATCHES);
          if (captureGroups && env != null && env != Collections.EMPTY_MAP) {
            int groupCount = m.groupCount();
            for (int i = 0; i <= groupCount; i++) {
              env.put("$" + i, m.group(i));
            }
          }
          return AviatorBoolean.TRUE;
        } else {
          return AviatorBoolean.FALSE;
        }
      case JavaType:
        AviatorJavaType javaType = (AviatorJavaType) other;
        final Object javaValue = javaType.getValue(env);
        if (TypeUtils.isString(javaValue)) {
          return this.match(new AviatorString(String.valueOf(javaValue)), env);
        } else {
          throw new ExpressionRuntimeException(
              this.desc(env) + " could not match " + other.desc(env));
        }
      default:
        throw new ExpressionRuntimeException(
            this.desc(env) + " could not match " + other.desc(env));
    }

  } 
                            #location 9 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                              @Override
  public AviatorObject match(AviatorObject other, Map<String, Object> env) {
    switch (other.getAviatorType()) {
      case String:
        AviatorString aviatorString = (AviatorString) other;
        Matcher m = this.pattern.matcher(aviatorString.lexeme);
        if (m.matches()) {
          boolean captureGroups =
              AviatorEvaluator.getOption(Options.PUT_CAPTURING_GROUPS_INTO_ENV);
          if (captureGroups && env != null && env != Collections.EMPTY_MAP) {
            int groupCount = m.groupCount();
            for (int i = 0; i <= groupCount; i++) {
              env.put("$" + i, m.group(i));
            }
          }
          return AviatorBoolean.TRUE;
        } else {
          return AviatorBoolean.FALSE;
        }
      case JavaType:
        AviatorJavaType javaType = (AviatorJavaType) other;
        final Object javaValue = javaType.getValue(env);
        if (TypeUtils.isString(javaValue)) {
          return this.match(new AviatorString(String.valueOf(javaValue)), env);
        } else {
          throw new ExpressionRuntimeException(
              this.desc(env) + " could not match " + other.desc(env));
        }
      default:
        throw new ExpressionRuntimeException(
            this.desc(env) + " could not match " + other.desc(env));
    }

  }