In Debug conf case, the following WPT encrypted-media test "clearkey-mp4-playback-retrieve-persistent-license.https.html" craches. Here is the call stack : STDERR: ASSERTION FAILED: !m_valueOrException STDERR: ../../Source/WebCore/bindings/js/DOMPromiseProxy.h(221) : void WebCore::DOMPromiseProxy<WebCore::IDLVoid>::resolve() STDERR: 1 0x7fa422332ae5 WTFCrash STDERR: 2 0x7fa420bb115d WebCore::DOMPromiseProxy<WebCore::IDLVoid>::resolve() STDERR: 3 0x7fa420ba9ccc WebCore::MediaKeySession::sessionClosed() The test crashes in the function DOMPromiseProxy<IDLType>::resolve --> Source/WebCore/bindings/js/DOMPromiseProxy.h: 154 which is called by MediaKeySession::sessionClosed() --> Source/WebCore/Modules/encryptedmedia/MediaKeySession.cpp: 683
Here is a similar bug: Bug 175899 - ASSERTION FAILED: !m_valueOrException under FontFaceSet::completedLoading loading a Serious Eats page
No longer getting this crash.