'Expected hexadecimal character' exception from $cookie->fetch() after upgrade

[pandabadger]

When reading cookies that were encrypted using v4.8 in v5.1 I'm seeing exceptions with the message 'Expected hexadecimal character'.

RangeException: Expected hexadecimal character in vendor/paragonie/constant_time_encoding/src/Hex.php:132
Stack trace: #0 vendor/paragonie/halite/src/Cookie.php(139): ParagonIE\ConstantTime\Hex::decode() # 1 vendor/paragonie/halite/src/Cookie.php(100): ParagonIE\Halite\Cookie::getConfig()

I see non-hex version prefixes being passed if fails the hash_equals() check in getConfig(). Seemed OK after just removing the call to Hex::decode() at line 139 in Cookie.php, but haven't checked what other impact that could have.

Not a huge deal since can just invalidate the cookies and create new. But maybe something that could be patched for future versions?