SFCs shouldn't export anything besides their component, and this
eliminates one issue with tsc, while apparently also solving a hack. It
seems to work as before, also when multiples are on the same page.
Fixes 79 typescript errors. Discovered at least two bugs in
`notifications.ts`, and I'm pretty sure this feature was at least
partially broken and may still be, I don't really know how to test it.
After this, only like ~10 typescript errors remain in the codebase but
those are harder to solve.
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Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>
