Bug 216307 – Uncaught Exception: TypeError: null is not an object (evaluating 'this.listItemElement.classList')

• Status: RESOLVED
• Resolution: FIXED
• Component: Web Inspector

[Antoine Quint]

Uncaught Exception in Web Inspector with a ToT build.

Steps to Reproduce:
1. Go to https://ionicframework.com/docs and open the Web Inspector
2. In the iOS device on the right of the page, scroll down to "Modal" and click on that row
3. Click on the "Open Modal" button

Uncaught Exceptions:
-----------------------
 - TypeError: null is not an object (evaluating 'this.listItemElement.classList') (at DOMTreeElement.js:1449:41)
    _nodeTitleInfo @ DOMTreeElement.js:1449:41
    updateTitle @ DOMTreeElement.js:1314:55
    _updateModifiedNodes @ DOMTreeUpdater.js:128:46
    ? @ DOMTreeUpdater.js:53:34
    _execute @ Debouncer.js:132:29
    ? @ Debouncer.js:86:26
-----------------------

Notes:
Inspected URL:        https://ionicframework.com/docs
Loading completed:    true
Frontend User Agent:  Mozilla/5.0 (Macintosh; Intel Mac OS X 11_0) AppleWebKit/605.1.15 (KHTML, like Gecko)

[Radar WebKit Bug Importer]

<rdar://problem/68565824>

[Nikita Vasilyev]

In 2016, there was a very similar uncaught exception:
Bug 162123 - Uncaught Exception: null is not an object (evaluating 'this.listItemElement.classList')

[Nikita Vasilyev]

Created attachment 409633 [details]
Patch

[Nikita Vasilyev]

(In reply to Nikita Vasilyev from comment #3)
> Created attachment 409633 [details]
> Patch

This is essentially the same fix as in "Bug 162123 - Uncaught Exception: null is not an object (evaluating 'this.listItemElement.classList')" from 2016.

[Nikita Vasilyev]

A couple of hours ago I was able to reproduce this on http://jsbin.testim.io/geg/11. However, I can't reproduce it on that page now :/

The steps from Antoine still work reliably.

[Blaze Burg]

Comment on attachment 409633 [details]
Patch

r=me

[EWS]

Committed r267577: <https://trac.webkit.org/changeset/267577>

All reviewed patches have been landed. Closing bug and clearing flags on attachment 409633 [details].