FilePanel doesn't paginate any more in E2EE rooms

[ara4n]

It shows however many files that are already loaded in the timeline, but shows an infinispinner at the top rather than pulling in additional older files

[kittykat]

Not convinced I can reproduce in Element version: 1.7.34, olm version: 3.2.3. If I scroll right as far back as I can (to 2017, I'm not sure if there are any older files), I don't get the infinispinner even though most of the files in the history aren't loaded in the timeline. I do get a blank area though:

I can also get an empty FilePanel if I scroll up and down too fast, might be related? :

@gsouquet can you reproduce?

[ara4n]

It's definitely inconsistent to reproduce, but i swear i can. Right now repro is made hard by (in element nightly desktop) it taking about 10s to paginate each chunk of filepanel contents. Obviously it should be instant given it can query the local sqlcipher db. In fact, it looks to be completely stuck now, tight-looping on:

rageshake.js?432e:65 TypeError: Cannot read property 'eventIdToTimeline' of undefined
    at eval (webpack-internal:///240:715)
    at Array.forEach (<anonymous>)
    at EventIndex.populateFileTimeline (webpack-internal:///240:714)
    at async paginationMethod (webpack-internal:///240:767)
    at async Promise.all (://vector/webapp/index 0)
    at async ScrollPanel.eval [as checkFillState] (webpack-internal:///1210:206)

will rageshake.

[SimonBrandner]

This is caused by the fact that we're accessing _timline on https://github.com/matrix-org/matrix-react-sdk/blob/develop/src/indexing/EventIndex.ts#L863. This doesn't exist anymore and it is private now