OID 2.999 decoded wrong about asn1 HOT 5 CLOSED

#!/usr/bin/php
<?php

declare(strict_types=1);

require_once "vendor/autoload.php";

use ASN1\Element;
use ASN1\Type\Structure;
use ASN1\Type\UnspecifiedType;
use ASN1\Type\Constructed\Sequence;
use ASN1\Type\Primitive\Boolean;
use ASN1\Type\Primitive\NullType;
use ASN1\Type\Primitive\UTF8String;
use ASN1\Component\Identifier;
use ASN1\Type\Primitive\Integer;
use ASN1\Type\Tagged\ExplicitlyTaggedType;
use ASN1\Type\Primitive\ObjectIdentifier;

function oid_test($oidx, $expected_der) {
  $fail = false;

  // First, encode the OID

  $seq = new Sequence(
      new ExplicitlyTaggedType(
          1, new ObjectIdentifier($oidx)
      )
  );
  $der = $seq->toDER();

  // First test: Check if DER encoding fits (create testcases at https://misc.daniel-marschall.de/asn.1/oid-converter/online.php )

  $string = substr($der,4); // remove SEQUENCE
  $der_hexdump = '';
  for ($i = 0; $i < strlen($string); $i++) {
      $der_hexdump .= str_pad(dechex(ord($string[$i])), 2, '0', STR_PAD_LEFT) . ' ';
  }
  if (strtoupper(trim($der_hexdump)) != strtoupper(($expected_der))) {
        echo "DER ENCODING MISMATCH: $oidx (is $der_hexdump , should be $expected_der)\n";
        $fail = true;
  }

  // Second test: Now check if decoding the encoded OID brings the same OID

  $seq = UnspecifiedType::fromDER($der)->asSequence();

  if ($oidx != $seq->at(0)->asTagged()->asExplicit()->asObjectIdentifier()->oid()) {
        echo "ENCODE/DECODE MISMATCH: $oidx != ".$seq->at(0)->asTagged()->asExplicit()->asObjectIdentifier()->oid()."\n";
        $fail = true;
  }

  if (!$fail) {
        echo "OK: $oidx\n";
  }
}

oid_test("1.3.6", '06 02 2B 06');
oid_test("1.3.6.9999999999999999999999999999999999999999999999999999999999999999999999999999999999999991", '06 2C 2B 06 A8 9B C7 AF C5 EF 8E 9C F5 CD 96 9B 86 DC BD D8 F1 E4 93 B9 ED D6 B4 98 E0 A3 9E DB 94 8F FF FF FF FF FF FF FF FF FF FF FF 77');
oid_test("2.1", '06 01 51');
oid_test("0.39", '06 01 27');
oid_test("1.39", '06 01 4F');
oid_test("2.40", '06 01 78');
oid_test("2.49", '06 02 81 01');
oid_test("2.999", '06 02 88 37');
oid_test("2.99999999999999999999999999999999999999999999999999999999999999999999999991", '06 24 81 E2 B2 96 93 A4 EE B6 D6 94 E3 A5 D2 E3 E3 FB DA AD E8 E5 82 8E 85 CA BF 90 80 80 80 80 80 80 80 80 80 47');