Bug 1967425 - remove faulty check for sessionStorage to prevent uncau…

[bershanskiy]

If user instructs User Agent to block cookies, every access to sessionStorage outside of try-catch block results in an error. Prior to this commit, setDebugOptionsFromSessionStorage() contained a faulty check for this case leading to unpredictable breakages in glean embedders. In particular, Glean was breaking pages on MDN https://developer.mozilla.org/

For details see: mdn/yari#13039

This is just one of many ways o fix the bug. Specifically, I removed faulty check in setDebugOptionsFromSessionStorage() in favor of a properly working check (the try-catch block) in getDebugOptionFromSessionStorage().

Tests:
I did not add any tests here because I did not any extra functionality, just removed a faulty check in favor of a functional one.

Changelog:
Updated CHANGELOG.md with a reference to this PR.

Documentation:
This change does not require any documentation.

Pull Request checklist

• Quality: Make sure this PR builds and runs cleanly.
  • Inside the glean/ folder, run:
    • npm run test Runs all tests
    • npm run lint Runs all linters
• Tests: This PR includes thorough tests or an explanation of why it does not
• Changelog: This PR includes a changelog entry to CHANGELOG.md or an explanation of why it does not need one
• Documentation: This PR includes documentation changes, an explanation of why it does not need that or a follow-up bug has been filed to do that work
  • Documentation should be added to The Glean Book when making changes to Glean's user facing API
    • When changes to the Glean Book are necessary, link to the corresponding PR on the mozilla/glean repository
  • Documentation should be added to the Glean.js developer documentation when making internal code changes

[Dexterp37]

@bershanskiy @travis79 if we remove this, wouldn't we hit what #1788 was supposed to fix, again?

Or do we always call this after getDebugOptions..?

[bershanskiy]

getDebugOptionFromSessionStorage() catches this exception properly (lines 73-82):

const getDebugOptionFromSessionStorage = (
  option: DebugOptionValue
): string | undefined => {
  try {
    return sessionStorage.getItem(`Glean.${option.toString()}`) || undefined;
  } catch (e) {
    console.warn(e);
    return undefined;
  }
};

This PR removes one faulty redundant check to let the code execution to actually reach the proper try-catch.