Use always innerException for Task.AsUniTask

[hadashiA]

refs: #422

After #486, There was some further discussion.

UniTask is a world line like Task when there is only await, so it may be possible to throw away other exceptions to match the behavior of await Task...

So, if await Task.WhenAll(...).AsUniTask() throws an exception, always use inner exception just like await Task.WhenAll(...).

[hadashiA]

@neuecc I added handling of cases where InnerExceptions is empty.. !

[neuecc]

good!

[krisrok]

Good to see this resolved but I don't get why my previous PR #428 was closed as this basically did the same thing. Except my solution also accounts for nested AggregateExceptions which yours does currently not.

@hadashiA please have look here:
krisrok/UniTask@62a2a2e...krisrok:UniTask:feature/asunitask-always-unwrap-aggregateexception-before-tests

[hadashiA]

@krisrok

Good to see this resolved but I don't get why my previous PR #428 was closed as this basically did the same thing.

My understanding is that the decision was made because the behavior of handling only the first one of InnerExceptions comes only from the Task world, and they did not want to bring that into UniTask in general.

Except my solution also accounts for nested AggregateExceptions which yours does currently not.

I see. Perhaps your implementation could be superior. I will check. Thanks.

[krisrok]

My understanding is that the decision was made because the behavior of handling only the first one of InnerExceptions comes only from the Task world, and they did not want to bring that into UniTask in general.

You're right, and this is no easy decision as we can read on similar discussions on the .NET repos. I personally would just want UniTask to be as close to the expectations of a "normal" .NET user who already knows Task and its behaviours. This is of course just my sole opinion.

I'll quote myself from here:

To reproduce .NET's behaviour, UniTask would have to always return the AggregateException's first exception regardless if there is more.

But this poses a problem because in UniTask's implementation you cannot access e.g. UniTask.Exception afterwards, you only ever get the thrown exception.

Task on the other hand has the Exception property which still holds the AggregateException even though it never throws an aggregate, only the first Exception. You'd have to actively look at Task.Exception to know if there's more.

If you want some tests regarding UniTask-Task-parity in regards of exceptions you can have a look at this branch.