Regression: "ReferenceError: docById is not defined" logs in console on master #4921
Description
Description: I have noticed that the ReferenceError: docById is not defined error has returned on the master branch (live website). Although the application interface appears to load, this error is consistently logged in the browser console during initialization.
Steps to Reproduce:
Open musicblocks.sugarlabs.org.
Open the Browser Console (F12).
Reload the page.
Actual Behavior: The browser console logs: Uncaught ReferenceError: docById is not defined (Source: (index):113 or activity.js).
Expected Behavior: The application should initialize cleanly without throwing ReferenceErrors in the console.
Technical Context:
This appears to be a regression of Issue #4292 / PR #4295.
The error suggests that the non-standard docById helper is undefined in the production environment.
Fix Proposed: I have prepared a fix that replaces the undefined helper with standard document.getElementById to permanently resolve this console error.
