An error occurs: "[VAPID] Private key should be 32 bytes long when decoded".

[melnikov-m-i]

When specifying a key in pem format, an error occurs. Namely, in the VAPID class, in the validate method.
The following point is confusing:

// Line: 57
$vapid['privateKey'] = base64_encode(str_pad(Base64Url::decode($jwk->get('d')), 2 * self::PRIVATE_KEY_LENGTH, '0', STR_PAD_LEFT));

// Line: 76
if (Utils::safeStrlen($privateKey) !== self::PRIVATE_KEY_LENGTH) {
    throw new \ErrorException('[VAPID] Private key should be 32 bytes long when decoded.');
}

That is, first the length of the key is doubled, adding 0 to the left. And then it is compared with the normal length.
Is this a mistake? Or not? Can someone explain it to me, if it's not too much trouble.

[melnikov-m-i]

Resolved in #414 and merged into version 9.