bat_fullcalendar_timeline.js: Errors in javascript console due to incorrect null and boolean values

Attached patch should fix issue with boolean and null in javascript file.

Aaand patch in #2 didn't apply after all due to whitespace issues, so re-rolled

The patch in issue https://www.drupal.org/project/bat/issues/3404353 🐛 bat_fullcalendar_timeline.js?v=10.1.6:251 Uncaught TypeError: Cannot set properties of undefined (setting 'url') Needs review also addresses the same issues as my patch, and since that one also fixes some other issues I suggest using it instead.

that's a pretty tricky issue https://www.drupal.org/project/coding_standards/issues/3259288 →

fixed in https://www.drupal.org/project/bat/releases/8.x-10.x-dev →