folds in HTML editor sometimes disappear

Nobody has claimed this yet.

This has been bugging me for a long time but I just now got around to narrowing it down to a simple test case.

Sometimes, in the webpage environment the "folds" information seems to get lost or corrupted. I know there's a folds[ ] array in the scratchpad data, I assume something is going wrong there.

To demonstrate the issue: Visit https://www.khanacademy.org/computer-programming/trying-to-reproduce-2-editor-bugs/6653234476351488 and make a spin-off. Note that there is a triangle next to line 49.

On line 49, click the fold triangle to fold up the `bar` object that's inside the `foo()` function. Save the project, and refresh the page. You should no longer see a triangle by line 49 or be able to collapse/fold up that object.

If you hit the spacebar on line 49, the triangle appears. You can then backspace the space and fold up your object/function/whatever. Save the project again with it folded up and the triangle disappears on you again.

This frustrates me often on my large projects, as I often try to use the keyboard shortcut ALT-0 to collapse everything and not everything folds up until I manually go through and add spaces all over the place and backspace them or I just fumble around saving/reloading my project until the editor cooperates.

(If this isn't reproducible, or description isn't clear, let me know and I'll include pictures or screencast.)

I have only seen this issue in the HTML edtior, not the JS+PJS editor.

Start by reproducing the issue in the linked HTML editor project: fold the object on line 49, save, refresh, and check whether the fold marker remains. Compare the saved folds data before and after reload; done means folds persist and the object can still be collapsed after saving and refreshing.

Written by the indexing model from the issue text.