Getting a couple of those exceptions in imported/w3c/web-platform-tests/html/semantics/embedded-content/media-elements/interfaces/TextTrack/activeCues.html imported/w3c/web-platform-tests/html/semantics/embedded-content/media-elements/track/track-element/track-api-texttracks.html
Also: imported/w3c/web-platform-tests/html/semantics/embedded-content/media-elements/track/track-element/track-cue-inline.html [ Failure ] imported/w3c/web-platform-tests/html/semantics/embedded-content/media-elements/track/track-element/track-delete-during-setup.html [ Failure ] imported/w3c/web-platform-tests/html/semantics/embedded-content/media-elements/track/track-element/track-selection-metadata.html [ Failure ]
Error comes from the controlsAreHidden() function in mediaControlsBase.js, where the `panel.parentElement` is null due to the controls currently not being present.
Also: imported/w3c/web-platform-tests/preload/single-download-preload.html [ Failure ]
All these tests started to pass since [r257130-r257133] onwards: * imported/w3c/web-platform-tests/html/semantics/embedded-content/media-elements/interfaces/TextTrack/activeCues.html * imported/w3c/web-platform-tests/html/semantics/embedded-content/media-elements/track/track-element/track-api-texttracks.html * imported/w3c/web-platform-tests/html/semantics/embedded-content/media-elements/track/track-element/track-cue-inline.html * imported/w3c/web-platform-tests/html/semantics/embedded-content/media-elements/track/track-element/track-delete-during-setup.html * imported/w3c/web-platform-tests/html/semantics/embedded-content/media-elements/track/track-element/track-selection-metadata.html: * imported/w3c/web-platform-tests/preload/single-download-preload.html Likely fixed in r257133. Closing bug. Gardened in https://bugs.webkit.org/show_bug.cgi?id=208987.