fix(auth): ensure isTokenExpired returns strict boolean #6002

[MMilosz]

References

• AuthService test unit tests fail more frequently than other test suites in CI #6002

Description

This PR fixes isTokenExpired() to return true for missing tokens (null or undefined), which could potentially reoslve #6002.

Instructions for Reviewers

This PR:

• adds two test cases for null/undefined token scenarios
• changes the return clause in isTokenExpired()

// original
public isTokenExpired(token?: AuthTokenInfo): boolean {
  token = token || this.getToken();
  return token && token.expires < Date.now();
}

source

A return value here can be true, false, or null if local storage has no token, or undefined if NgRx store hasn't initialized yet-these cases could cause problems when methods expected a boolean return value.

The fix ensures isTokenExpired() always returns a proper true/false boolean.

To test, please verify if that all unit tests pass and that no token behavior changes occur after logging into a site.

Checklist

• My PR is created against the main branch of code (unless it is a backport or is fixing an issue specific to an older branch).
• My PR is small in size (e.g. less than 1,000 lines of code, not including comments & specs/tests), or I have provided reasons as to why that's not possible.
• My PR follows all coding best practices based on the Code Conventions Guide
• My PR passes ESLint validation using npm run lint
• My PR doesn't introduce circular dependencies (verified via npm run check-circ-deps)
• My PR includes TypeDoc comments for all new (or modified) public methods and classes. It also includes TypeDoc for large or complex private methods.
• My PR passes all specs/tests and includes new/updated specs or tests based on the Code Testing Guide.
• My PR aligns with Accessibility guidelines if it makes changes to the user interface.
• My PR uses i18n (internationalization) keys instead of hardcoded English text, to allow for translations.
• My PR includes details on how to test it. I've provided clear instructions to reviewers on how to successfully test this fix or feature.
• If my PR includes new libraries/dependencies (in package.json), I've made sure their licenses align with the DSpace BSD License based on the Licensing of Contributions documentation.
• If my PR includes new features or configurations, I've provided basic technical documentation in the PR itself.
• If my PR fixes an issue ticket, I've linked them together.