fix(stepper): throw when out-of-bounds value is assigned to selectedIndex

[crisbeto]

Throws better error when an out-of-bounds value is assigned to the selectedIndex.

[mmalerba]

Shouldn't we actually throw an error in this case? That way the user knows what they're doing wrong rather than trying to track down strange behavior. Maybe just throw a custom error instead of whatever is thrown now that explains better?

[crisbeto]

That also makes sense, but I went with this approach, because it’s consistent with what we do in the tabs.

[mmalerba]

@andrewseguin do you think the tabs behavior should change or this should match what tabs currently does?

[andrewseguin]

As a developer I'd probably want to see an error rather than the component fixing itself. I think though that this fix is in favor of the end-user who runs across an edge case where the developer made a mistake.

I vote for changing both tabs and this to throw an error and be clear to the developer that their logic isn't right

[crisbeto]

Switched it to throw an error @mmalerba @andrewseguin.

[crisbeto]

@andrewseguin I'm looking at adding similar changes to the tabs and there's a case that we didn't consider: the tabs/steps could be added asynchronously in which case the consumer starts getting into race conditions instead of having the component default to zero.

[andrewseguin]

Hmm that's an interesting point, so we expect that the selected index stays as out of bounds in case the steps/tabs are updated later?

[crisbeto]

No, it's more like we set it to zero when it's out of bounds, rather than throw an error, because we can't know whether any new elements are going to come in. @andrewseguin

[andrewseguin]

In that case, should we expect the developer to still be accurate and change the selectedIndex when the async call is complete, and otherwise keep it at 0?

[crisbeto]

I suppose, but that ends up being a lot more inconvenient.

[andrewseguin]

Probably needs more discussion but this is fine if you want this behavior for now

[angular-automatic-lock-bot]

This issue has been automatically locked due to inactivity.
Please file a new issue if you are encountering a similar or related problem.

Read more about our automatic conversation locking policy.

_{This action has been performed automatically by a bot.}