Emoji selector crashes the message editor in Android / Chrome

bug
3

I can reproduce. Follows the stack trace:

_application-bfbda341c2eb6dd7d61c681e17bdccec057c30e045ddc332927a7363150e9b1b.js:16386 Uncaught TypeError: Cannot read property '0' of null
    at HTMLLIElement.<anonymous> (application-bfbda341c2eb6dd7d61c681e17bdccec057c30e045ddc332927a7363150e9b1b.br.js:1)
    at HTMLLIElement.dispatch (ember_jquery-36a23101c869ab0dc53fc908de69adb785731593573d32bdeef416acc1076ef4.br.js:1)
    at HTMLLIElement.d.handle (ember_jquery-36a23101c869ab0dc53fc908de69adb785731593573d32bdeef416acc1076ef4.br.js:1)
(anonymous) @ application-bfbda341c2eb6dd7d61c681e17bdccec057c30e045ddc332927a7363150e9b1b.br.js:1
dispatch @ ember_jquery-36a23101c869ab0dc53fc908de69adb785731593573d32bdeef416acc1076ef4.br.js:1
d.handle @ ember_jquery-36a23101c869ab0dc53fc908de69adb785731593573d32bdeef416acc1076ef4.br.js:1

That is this line

https://github.com/discourse/discourse/blob/master/app/assets/javascripts/discourse/app/lib/autocomplete.js#L308

Error happens because selectedOption is 0 (single suggestion aka the first) while autocompleteOptions is somehow null.

Investigating why now…

So I’m not sure why so far. At first I was suspecting this PR from @Osama

https://github.com/discourse/discourse/pull/11637

But I added quite a few breakpoints and can’t really find “who” is mutating autocompleteOptions and setting it as null.

Having autocompleteOptions be from the scope of the parent closure from two levels up is also quite weird and makes the code a bit hard to follow up/debug.

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