Transition TypeError with multiple listeners

[KaelWD]

Version

3.0.5

Reproduction link

https://codepen.io/kaelwd/pen/poNNMQN?editors=1010

Steps to reproduce

Click the toggle button

What is expected?

The grey square should hide

What is actually happening?

Uncaught (in promise) TypeError: onLeave is not a function

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Worked in Vue 2: https://codepen.io/kaelwd/pen/poNNMBe?editors=1010

[LinusBorg]

The current implementation allows to receive an array of callbacks in the transition's prop definition, but calls it like a function, without checking for an array:

I assume onLeave should be called with callHook like the other hooks, but right now I'm not sure if there's any side effect with callHook's async error handling that should be taken into consideration, will need to take a closer look tomorrow after some sleep.

Likely a simple fix.

[nrgnrg]

callHook was removed from Transition in #1145 bf84ac8.

Error handling is done by BaseTransition but callHook wasn't replaced with something that can call an array of functions if that's what it is given.

I'm happy to look at this but I'm just unclear on this condition if (!(onLeave && onLeave.length > 1)) which has to be true to call whenTransitionEnds. Not calling that means the transition never completes. But since onLeave doesn't mutate there seems to be no reason to check it's length to call or not call whenTransitionEnds?

[edison1105]

onLeave is an Array

[LinusBorg]

Was already working on a solution, got a bit stumped by some Type confusion on my side. Will give it another go now though.