TypeError: Cannot read properties of null (reading 'removeObserver')

[ildar-shamilov-clearscale]

What happened and what did you expect to happen?

After migrating to v3 from v2.

Calling AudioVideoFacade.stop() sometimes throws exception:

LoggerService.ts:89 TypeError: Cannot read properties of null (reading 'removeObserver')
at DefaultAudioVideoController.uninstallPreStartObserver (DefaultAudioVideoController.js:210:1)
at DefaultAudioVideoController. (DefaultAudioVideoController.js:221:1)
at Generator.next ()
at DefaultAudioVideoController.js:10:1
at new Promise ()
at push.../node_modules/amazon-chime-sdk-js/build/audiovideocontroller/DefaultAudioVideoController.js.__awaiter (DefaultAudioVideoController.js:6:1)
at handleClosed (DefaultAudioVideoController.js:218:1)
at Object.handleSignalingClientEvent (DefaultAudioVideoController.js:226:1)
at DefaultSignalingClient.sendEvent (DefaultSignalingClient.js:291:1)
at DefaultSignalingClient.closeEventHandler (DefaultSignalingClient.js:23:1)

Have you reviewed our existing documentation?

• GitHub issues
• FAQs page
• README page
• Feature-specific guides

Reproduction steps

Calling AudioVideoFacade.stop()

Amazon Chime SDK for JavaScript version

3.2.0

What browsers are you seeing the problem on?

Chrome latest

Browser version

Chrome latest

Meeting and Attendee ID Information.

No response

Browser console logs

LoggerService.ts:89 TypeError: Cannot read properties of null (reading 'removeObserver')
at DefaultAudioVideoController.uninstallPreStartObserver (DefaultAudioVideoController.js:210:1)
at DefaultAudioVideoController. (DefaultAudioVideoController.js:221:1)
at Generator.next ()
at DefaultAudioVideoController.js:10:1
at new Promise ()
at push.../node_modules/amazon-chime-sdk-js/build/audiovideocontroller/DefaultAudioVideoController.js.__awaiter (DefaultAudioVideoController.js:6:1)
at handleClosed (DefaultAudioVideoController.js:218:1)
at Object.handleSignalingClientEvent (DefaultAudioVideoController.js:226:1)
at DefaultSignalingClient.sendEvent (DefaultSignalingClient.js:291:1)
at DefaultSignalingClient.closeEventHandler (DefaultSignalingClient.js:23:1)

[xuesichao]

Hi @ildar-shamilov-clearscale , thanks for reporting this issue.

It seems this issue happens because the signalingClient is null. JS SDK initialize a signalingClient instance when calling AudioVIdeoFacade.start() or reconnecting. The signalingClient is set to only when re-connection failed and disconnected.

Could you please provide us more details for your use cases, and how you encountered this issue? If you can find a stable way to reproduce this issue, that would help us a lot.

[ildar-shamilov-clearscale]

Probably when i am calling .stop() before .start()

[devalevenkatesh]

@ildar-shamilov-clearscale could you please provide browser console logs for this issue? I tried calling .stop() before .start() but did not ran into any such issue. Seems like the meetingSessionContext.signalingClient is not valid in uninstallPreStartObserver here. I suspect if these two lines race sometime.
https://github.com/aws/amazon-chime-sdk-js/blob/main/src/audiovideocontroller/DefaultAudioVideoController.ts#L737-L738

The uninstallPreStartObserver is called when the signaling client received a close event. Thus it might be happening that the signalingClient.closeConnection triggers the event but the signalingClient is nullified in above two lines.

Created a PR to fix the error. But I think we need console logs to root cause.

[devalevenkatesh]

Closing this issue as we have merged the PR with a fix. Please let me know if you have more issues.