CT tried to removeListener on something that wasn't a listener

[KatieWoe]

john-travoltage : multitouch-fuzz : unbuilt
https://bayes.colorado.edu/continuous-testing/ct-snapshots/1628759848901/john-travoltage/john-travoltage_en.html?continuousTest=%7B%22test%22%3A%5B%22john-travoltage%22%2C%22multitouch-fuzz%22%2C%22unbuilt%22%5D%2C%22snapshotName%22%3A%22snapshot-1628759848901%22%2C%22timestamp%22%3A1628763588058%7D&brand=phet&ea&fuzz&fuzzPointers=2&memoryLimit=1000&supportsPanAndZoom=false
Query: brand=phet&ea&fuzz&fuzzPointers=2&memoryLimit=1000&supportsPanAndZoom=false
Uncaught Error: Assertion failed: tried to removeListener on something that wasn't a listener
Error: Assertion failed: tried to removeListener on something that wasn't a listener
at window.assertions.assertFunction (https://bayes.colorado.edu/continuous-testing/ct-snapshots/1628759848901/assert/js/assert.js:25:13)
at Timer.removeListener (https://bayes.colorado.edu/continuous-testing/ct-snapshots/1628759848901/axon/js/TinyEmitter.js:135:7)
at callback (https://bayes.colorado.edu/continuous-testing/ct-snapshots/1628759848901/axon/js/Timer.js:33:16)
at Timer.emit (https://bayes.colorado.edu/continuous-testing/ct-snapshots/1628759848901/axon/js/TinyEmitter.js:86:9)
at https://bayes.colorado.edu/continuous-testing/ct-snapshots/1628759848901/joist/js/Sim.js:303:17
at Action.execute (https://bayes.colorado.edu/continuous-testing/ct-snapshots/1628759848901/axon/js/Action.js:227:18)
at Sim.stepSimulation (https://bayes.colorado.edu/continuous-testing/ct-snapshots/1628759848901/joist/js/Sim.js:1083:31)
at Sim.stepOneFrame (https://bayes.colorado.edu/continuous-testing/ct-snapshots/1628759848901/joist/js/Sim.js:1073:12)
at Sim.runAnimationLoop (https://bayes.colorado.edu/continuous-testing/ct-snapshots/1628759848901/joist/js/Sim.js:1051:12)
id: Bayes Chrome
Snapshot from 8/12/2021, 3:17:28 AM

[jessegreenberg]

This seems pretty rare, and I am not sure what is causing it yet. Fuzzing on my local machine with the same query parameters isn't showing it, and it isn't in the last 10 CT collumns.

But I have seen this once before as well on CT before the snapshot @KatieWoe posted so I don't think it is gone.

[jessegreenberg]

The case that we are running into is this in Timer.setTimeout

        // make sure that this callback hasn't already been removed by another listener while emit() is in progress
        if ( this.hasListener( callback ) ) {
          listener();
          this.removeListener( callback );
        }

The listener must be removing itself so this.removeListener errors out.

[jessegreenberg]

I am seeing this in GFL:B as well in the last 10 CT cycles, must not be specific to this sim. Going to try to get it to happen there.

[jessegreenberg]

Found more information about why this is happening:

When a speech request is made, something is causing the queue to synchronously clear (and therefore remove timer listeners) from within the setTimeout listener.

[jessegreenberg]

I found it. What is happening is:

• voicingManager starts speaking from within the timeout
• For some reason, the SpeechSynthesis error event triggers. voicingManager.endSpeakingEmitter fires from that event.
• A listener on that Emitter sets another Property in VoicingToolbarItem that has yet another listener that eventually calls voicingManager.cancel().
• All listeners on the timer are remove in cancel, including the one that is currently firing. Then Timer.js tries to remove the timer that was already removed, causing the assertion.

endSpeakingEmitter being called on the error event seems correct to me, and I don't think there is anything wrong about the client usage. I think we need to be more graceful in voicingManager by not removing the listener in cancel() if cancel was initiated immediately from a request to speak.

[jessegreenberg]

This was fixed in the above commit. I was able to step through the problematic case and verify that the listener was not removed twice, but was successfully removed once at the end of the callback. Closing.