fix: options.priority ternary in serialize validation

[jonchurch]

closes #206

Assuming here this was not intentional

[jonchurch]

Im guessing Codecov is failing bc I opened from a fork, so no access to the secret

[blakeembrey]

Good catch, do you want to make both undefined in the ternaries? I don’t know why I didn’t do that the first time.

[jonchurch]

By both you mean the next block w/

  if (options.sameSite) {
    const sameSite =
      typeof options.sameSite === "string"
        ? options.sameSite.toLowerCase()
        : options.sameSite;

this needs to stay, at that part of the code sameSite can be boolean | <the valid strings>