Tutorial extension drawers occasionally fail to load

Describe the bug
We have a tutorial that depends on an extension. On rare occasions the drawers and text annotations for that extension fail to load.

A team member documented her experience with the attached screenshots. She had the bug and took a screenshot. Then she came back to it the next day on the same computer and browser and it worked. The reason one part is blacked out in the screenshots is because that annotation failed because of a syntax error, not the bug. The extension used was Forward-Education/pxt-solar

This has also been observed in our professional development sessions where everybody loads the same tutorial and 1 or 2 participants get this bug. Sometimes refreshing/clearing cache/re-opening a new tutorial fixes it, sometimes it doesn't. The extension used in those cases was climate-action-kits/pxt-fwd-edu.

To Reproduce
Unfortunately the bug cannot be reliably reproduced.

Screenshots

No source files, tests, or entry points are identified in the issue. Start by investigating how tutorial extensions load their drawers and text annotations, using Forward-Education/pxt-solar and climate-action-kits/pxt-fwd-edu as examples. Done means those extension elements load reliably for participants, including after opening the tutorial or refreshing.