angular: checkBindingNoChanges() attempting to check an index that does not exist

I’m submitting a…

[X] Bug report  

Minimal reproduction of the problem with instructions

@lishichao1002 was kind enough to provide a repro case at http://plnkr.co/edit/FcuEqLLp8UeS5JXinsGi?p=preview which is similar to what I’m seeing (the error seems limited to cases where visibility of a component is toggled).

To see the error:

1. Open the above Plunker
2. Open the Chrome console
3. Press “Open OK” to see that the overlay appears when it is opened with a direct function call
4. Press “Open Appear Error” to see the Cannot read property 'name' of undefined error in checkBindingNoChanges() when a binding is used to display the overlay.

Environment

Angular version: 5.2.2


Browser:
- [X] Chrome (desktop) version 64.0.3282.119
 

There seems to be a bug or unhandled error problem related to checkBindingNoChanges() in /core/src/view/util.ts.

The function looks like this:

export function checkBindingNoChanges(view, def, bindingIdx, value) {
    var /** @type {?} */ oldValue = view.oldValues[def.bindingIndex + bindingIdx];
    if ((view.state & 1 /* BeforeFirstCheck */) || !devModeEqual(oldValue, value)) {
        var /** @type {?} */ bindingName = def.bindings[def.bindingIndex].name;
        throw expressionChangedAfterItHasBeenCheckedError(Services.createDebugContext(view, def.nodeIndex), bindingName + ": " + oldValue, bindingName + ": " + value, (view.state & 1 /* BeforeFirstCheck */) !== 0);
    }
}

During unit testing, I’m intermittently getting an error from checkBindingNoChanges(): Cannot read property 'name' of undefined at checkBindingNoChanges

I was able to trigger this while “break on exceptions” was on, and took the following screenshot. checkBindingNoChanges() tries to look up the binding name via def.bindings[def.bindingIndex].name. But since def.bindingIndex is currently 20, this evaluates to def.bindings[20].name. But def.bindings only has 10 elements in it, which results in the error I’m seeing.

Unfortunately, I have no real way to try and build a repro case for this, since I have no idea how Angular is getting into this state. But something seems to be getting out of sync somewhere, possibly the compiler? Should there at least be a check to make sure the index that is being checked exists?