Race condition in unloading contact content

[dianabarsan]

Describe the bug Some feedback docs report this error:

Uncaught (in promise): TypeError: Cannot read properties of null (reading '_id')\nTypeError: Cannot read properties of null (reading '_id')\n    at t.<anonymous> (https://host/main.js?_sw-precache=hash:1:3077223)\n    at https://host/main.js?_sw-precache=hash:1:2623240\n    at Object.next (https://host/main.js?_sw-precache=hash:1:2623345)\n    at l (https://host/main.js?_sw-precache=hash:1:2622075)\n    at p.value (https://host/polyfills.js:1:10189)\n    at Object.onInvoke (https://host/main.js?_sw-precache=hash:1:2174490)\n    at p.value (https://host/polyfills.js:1:10128)\n    at p.value (https://host/polyfills.js:1:4280)\n    at https://host/polyfills.js:1:21025\n    at p.value (https://host/polyfills.js:1:10880)

This points to: https://github.com/medic/cht-core/blob/52605ac752bb40ab61ee1198fd7fe1bc0fbef982/webapp/src/ts/modules/contacts/contacts-content.component.ts#L256 where we don't nullcheck for validity of selectedContact before accessing the _id property.

The feedback doc was reported (unanimously) on /#/contacts, and almost half of the instances seemed to be triggered soon after the app was opened.

To Reproduce Steps to reproduce the behavior: TBD

Expected behavior No errors. We should gracefully handle not having a selected contact or the selected contact being unloaded.

Logs As above.

Environment

• Instance: live instance
• Browser: Webview?
• Client platform: Android
• App: webapp
• Version: 3.14.x

[kennsippell]

There are about 100 feedback docs/month due to this bug for production PiH instance.

[garethbowen]

I couldn't figure out how to reproduce this. The only path to the line that throws the error is already null checked so it shouldn't be possible. However it's clear from the error message what the fix is, so to be on the safe side I've just added a null check.

[garethbowen]

Ready for AT in 7603-null-check-contact

[tatilepizs]

Hi @garethbowen, what will be the correct way to test this ticket?

[garethbowen]

Sorry I should have been more clear... I didn't manage to reproduce it myself (even with breakpoints and so on). If you wouldn't mind just smoke testing:

• selecting a contact
• deselecting them (selecting another or moving to another tab)
• muting a contact

I think that'll be sufficient.

[tatilepizs]

Thank you for the details Gareth. I did a smoke test using the branch 7603-null-check-contact and create contacts, edit them, muted them, and created death reports, it and everything worked as expected. So I think that we are good and we can just merge it 🎉

[garethbowen]

Merged!