The event listeners are only applied in the ResourceDetailsSidebarPanel after it has initialLayout(). If the panel is created without ever being shown, each time it is hidden() it will attempt to remove the event listeners. Since it has not been initialLayout(), these event listeners would not have already been added.
Created attachment 312496 [details] Patch
Does this trigger benign assertions or something?
Comment on attachment 312496 [details] Patch View in context: https://bugs.webkit.org/attachment.cgi?id=312496&action=review > Source/WebInspectorUI/UserInterface/Views/ResourceDetailsSidebarPanel.js:94 > + this._needsToRemoveResourceEventListeners = false; Can you also put something up in the constructor that initializes this member variable.
Comment on attachment 312496 [details] Patch View in context: https://bugs.webkit.org/attachment.cgi?id=312496&action=review >> Source/WebInspectorUI/UserInterface/Views/ResourceDetailsSidebarPanel.js:94 >> + this._needsToRemoveResourceEventListeners = false; > > Can you also put something up in the constructor that initializes this member variable. Oh this is in the constructor (implicitly).
Created attachment 312558 [details] Patch (In reply to Joseph Pecoraro from comment #2) > Does this trigger benign assertions or something? Yes, it causes assertions in `removeEventListener` ``` console.assert(didDelete, "removeEventListener cannot remove " + eventType.toString() + " because it doesn't exist."); ```
The commit-queue encountered the following flaky tests while processing attachment 312558 [details]: transforms/hittest-translated-content-off-to-infinity-and-back.html bug 173222 (author: zalan@apple.com) imported/w3c/web-platform-tests/html/browsers/windows/browsing-context.html bug 172934 (author: youennf@gmail.com) The commit-queue is continuing to process your patch.
Comment on attachment 312558 [details] Patch Clearing flags on attachment: 312558 Committed r218049: <http://trac.webkit.org/changeset/218049>
All reviewed patches have been landed. Closing bug.