Fix js error about viewState being undefined
In change 355716 it was claimed that:
```
// viewState is set by gr-router in handleChangeRoute method and is
// never set to undefined
```
That claim is wrong, see `this.changeViewModel.setState(undefined);`
in the `setState()` method.
Release-Notes: skip
Change-Id: Ibb2bb27494ad100c235306313804b7947846c6e8
diff --git a/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view.ts b/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view.ts
index 6c1b681..d4627e2 100644
--- a/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view.ts
+++ b/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view.ts
@@ -2079,9 +2079,7 @@
// Private but used in tests.
viewStateChanged() {
- // viewState is set by gr-router in handleChangeRoute method and is never
- // set to undefined
- assertIsDefined(this.viewState, 'viewState');
+ if (!this.viewState) return;
if (this.isChangeObsolete()) {
// Tell the app element that we are not going to handle the new change
