Fix undefined route info error

[dmytro-krekota]

It is for fixing an error which I faced:
TypeError: Cannot read property 'name' of undefined

[rwjblue]

I'm vaguely worried about adding this sort of guard because it often covers up other underlying problems. Do you know why the value was undefined? Can you add a test that previously failed and now passes?

[sly7-7]

@rwjblue I'll look into it. There are some open issues mentionning this this Type Error, and currently there is an other spot in the router where we do this kind of check:

ember.js/packages/@ember/-internals/routing/lib/system/router.ts

Line 1496 in 56c3520

if (infos.length === 0) {

Thinking a bit about it, I can't see a legit case where the RouteInfos can be empty (maybe I misunderstand this thing, but for me that would mean there is no (active ?) route at all, which would be very surprising. (except maybe during the initial transition ?)
I don't know if I'm clear in this description, but in all cases, naively I thought after setupRouter(), there was at least one RouteInfo, the one concerning the ApplicationRoute.

@dmytro-krekota Can you describe the scenario where that error pops up ? Currently, this issue makes me think at this one: #11563

[dmytro-krekota]

@rwjblue I do not know why the value was undefined, will try to add a test.

@sly7-7 should be an initial transition, but I can not reproduce it now in my app.

[sly7-7]

@dmytro-krekota there has been (hopefully) some improvements in the router area, landed in 3.24.3 and 3.25.3. So maybe this is it ?

[dmytro-krekota]

@sly7-7 no, I use the 3.12.0 version. Maybe updating can help to fix it.

[sly7-7]

@sly7-7 should be an initial transition, but I can not reproduce it now in my app.

I'm confused here, you can't reproduce it even in your app on ember 3.12.0 version ?
When I reviewed some other issues ending up to this error (TypeError: Cannot read property 'name' of undefined), I think they were either playing with loading state, redirect during inititial transition, and query params (maybe with the refreshModel flag set to true)

[dmytro-krekota]

@sly7-7 yes.
No "refreshModel" in my code.
"Redirect during the initial transition" - can be, I have some manual route transitions.

[sly7-7]

Ok, so what about letting you some time to try to reproduce ? If it appears the issue is gone, could you then close this issue ?

[sly7-7]

Thank you @dmytro-krekota :) I'm assuming that's a good news, since you initial issue seems resolved, right ?

[patrickberkeley]

I'm seeing the originally reported/fixed issue on this PR after upgrading ember from 3.25.0 to 3.26.1 and using the Router service to call replaceWith instead of calling replaceWith on the route itself. Here's more of the call stack that leads to routeInfos being empty:

TypeError: Cannot read property 'name' of undefined     at Class._queryParamsFor 
(http://localhost:4204/assets/vendor.js:35463:59)     at ApplicationRoute.finalizeQueryParamChange 
(http://localhost:4204/assets/vendor.js:34405:29)     at Class.triggerEvent (http://localhost:4204/assets/vendor.js:35922:27)     
at PrivateRouter.triggerEvent (http://localhost:4204/assets/vendor.js:34763:43)     at PrivateRouter.finalizeQueryParamChange 
(http://localhost:4204/assets/vendor.js:78116:12)     at PrivateRouter.queryParamsTransition 
(http://localhost:4204/assets/vendor.js:77611:37)     at PrivateRouter.getTransitionByIntent 
(http://localhost:4204/assets/vendor.js:77683:37)     at PrivateRouter.transitionByIntent 
(http://localhost:4204/assets/vendor.js:77632:21)     at PrivateRouter.doTransition 
(http://localhost:4204/assets/vendor.js:77768:19)     at PrivateRouter.transitionTo 
(http://localhost:4204/assets/vendor.js:78240:19)

When I debug that stack, the new Transition the router creates does just have empty routeInfos. In fact everything on it is empty. This Transition is what is subsequently used to set private __STATE__ which is looked up and passed to _queryParamsFor.

Note, I only see this issue in tests.

[patrickberkeley]

I spoke too soon in my previous comment. After upgrading, I'm not occasionally seeing this error in my app too, not just in tests. In the app, the source of the error is empty routeInfos on the Transition in the Route model hook:

https://github.com/emberjs/ember.js/blob/ac201b8e3e52226dbc74daf7be476985f9109a61/packages/@ember/-internals/routing/lib/system/route.ts