CT should not be called if disposed

[KatieWoe]

Query: brand=phet&ea&fuzzBoard&a11y&memoryLimit=1000
Uncaught Error: Assertion failed: should not be called if disposed
Error: Assertion failed: should not be called if disposed
    at window.assertions.assertFunction (https://bayes.colorado.edu/continuous-testing/snapshot-1561528310946/assert/js/assert.js:22:13)
    at TinyEmitter.emit (https://bayes.colorado.edu/continuous-testing/snapshot-1561528310946/axon/js/TinyEmitter.js?bust=1561549596721:50:17)
    at BooleanProperty._notifyListeners (https://bayes.colorado.edu/continuous-testing/snapshot-1561528310946/axon/js/Property.js?bust=1561549596721:247:27)
    at BooleanProperty.set (https://bayes.colorado.edu/continuous-testing/snapshot-1561528310946/axon/js/Property.js?bust=1561549596721:160:14)
    at BooleanProperty.set value [as value] (https://bayes.colorado.edu/continuous-testing/snapshot-1561528310946/axon/js/Property.js?bust=1561549596721:316:34)
    at PressListener.interrupt (https://bayes.colorado.edu/continuous-testing/snapshot-1561528310946/scenery/js/listeners/PressListener.js?bust=1561549596721:429:43)
    at TextPushButton.interruptInput (https://bayes.colorado.edu/continuous-testing/snapshot-1561528310946/scenery/js/nodes/Node.js?bust=1561549596721:1936:40)
    at TextPushButton.blur (https://bayes.colorado.edu/continuous-testing/snapshot-1561528310946/scenery/js/accessibility/Accessibility.js?bust=1561549596721:531:18)
    at Function.set focus [as focus] (https://bayes.colorado.edu/continuous-testing/snapshot-1561528310946/scenery/js/display/Display.js?bust=1561549596721:1730:23)
    at Object.blur (https://bayes.colorado.edu/continuous-testing/snapshot-1561528310946/scenery/js/input/A11yPointer.js?bust=1561549596721:65:33)
id: Bayes Chrome
Approximately 6/25/2019, 11:51:50 PM
build-an-atom : phet-io-tests : assert
9 out of 9 tests passed. 0 failed.

Approximately 6/25/2019, 11:51:50 PM
build-an-atom : phet-io-tests : no-assert
9 out of 9 tests passed. 0 failed.

Approximately 6/25/2019, 11:51:50 PM

[jbphet]

This issue happened three times, and hasn't happened since. The root of the stack is in A11yPointer.js in the 'blur' function, so this seems like this is accessibility related. I looked at that file and some others that are related and didn't see any recent changes. I also fuzz tested locally for ~20 minutes without hitting this issue, so I'm not sure where to go with it from here.

@jessegreenberg - do you have any immediate insights? If not, I'd suggest assigning it back to QA to watch and see if it recurs before we spend any more time on it.

[jessegreenberg]

Thanks, this is a11y related, I will take a look. I was able to hit it after running the sim with ?fuzzBoard&a11y, but it still took a while (~4 minutes of fuzzing in the background).

[jessegreenberg]

The trace looks different than what was reported when I hit the issue:

[jessegreenberg]

I found that this can be reproduced just by clicking the "Next" button with a spacebar in the game screen.

[jessegreenberg]

This has likely always been an issue but the assertion was added somewhat recently for https://github.com/phetsims/axon/issues/242. From that issue there is a comment that mentiones

pointed out that this seems to happen when clicking a button causes it to dispose itself.

Which is exactly what is happening here.

[jessegreenberg]

There are two ways to hit this currently - 1) The PressListener can be disposed before PressListener interrupt function is called internally by scenery because the button receives a blur event, and on blur interruptInput is called. 2) The PressListener can be disposed before the end of _a11yLooksPressedInterval when the button disposes itself and so we try to set the value of a11yClickingProperty after it has been disposed.

[jessegreenberg]

The buttons are working after the above commit, and I haven't seen the issue show up while running ?fuzzBoard. Ill check again after a few CT iterations and then close if it doesn't show up again.

[jessegreenberg]

Verified fixed, closing