Hi Team, While importing custom-elements/registries/ from WPT Upstream in PR - https://github.com/WebKit/WebKit/pull/53067 , I noticed that we crash on debug Mac-wk2 for 'Element-innerHTML.html'. **** Crash Log *** stderr: ASSERTION FAILED: registry /Volumes/Data/worker/macOS-Tahoe-Debug-Build-EWS/build/Source/WebCore/bindings/js/JSCustomElementInterface.cpp(228) : void WebCore::JSCustomElementInterface::upgradeElement(Element &) 1 0x3046d40e0 WebCore::JSCustomElementInterface::upgradeElement(WebCore::Element&) 2 0x3053fe144 WebCore::CustomElementReactionQueueItem::invoke(WebCore::Element&, WebCore::JSCustomElementInterface&) 3 0x3053fdea0 WebCore::CustomElementReactionQueue::invokeAll(WebCore::Element&) 4 0x3053feb0c WebCore::CustomElementQueue::invokeAll() 5 0x3053fe8d4 WebCore::CustomElementQueue::processQueue(JSC::JSGlobalObject*) 6 0x300b4358c WebCore::CustomElementReactionStack::~CustomElementReactionStack() 7 0x300b432e8 WebCore::CustomElementReactionStack::~CustomElementReactionStack() 8 0x301486a68 WebCore::setJSElement_innerHTMLSetter(JSC::JSGlobalObject&, WebCore::JSElement&, JSC::JSValue) 9 0x30133e7c8 bool WebCore::IDLAttribute<WebCore::JSElement>::set<&WebCore::setJSElement_innerHTMLSetter(JSC::JSGlobalObject&, WebCore::JSElement&, JSC::JSValue), (WebCore::CastedThisErrorBehavior)0>(JSC::JSGlobalObject&, long long, long long, JSC::PropertyName) 10 0x30133e6ac WebCore::setJSElement_innerHTML(JSC::JSGlobalObject*, long long, long long, JSC::PropertyName) 11 0x12de5bbd0 WTF::FunctionPtr<(WTF::PtrTag)30177, bool (JSC::JSGlobalObject*, long long, long long, JSC::PropertyName), (WTF::FunctionAttributes)1>::operator()(JSC::JSGlobalObject*, long long, long long, JSC::PropertyName) const 12 0x12df655e8 JSC::JSObject::putInlineSlow(JSC::JSGlobalObject*, JSC::PropertyName, JSC::JSValue, JSC::PutPropertySlot&) 13 0x12d49a0e4 JSC::JSObject::putInlineForJSObject(JSC::JSCell*, JSC::JSGlobalObject*, JSC::PropertyName, JSC::JSValue, JSC::PutPropertySlot&) 14 0x12d499dcc JSC::JSCell::putInline(JSC::JSGlobalObject*, JSC::PropertyName, JSC::JSValue, JSC::PutPropertySlot&) 15 0x12d49de10 JSC::JSValue::putInline(JSC::JSGlobalObject*, JSC::PropertyName, JSC::JSValue, JSC::PutPropertySlot&) 16 0x12db2bf24 llint_slow_path_put_by_id 17 0x12ea6ecec jsc_llint_llintOpWithMetadata__llintOpWithReturn__llintOp__commonOp__fn__fn__makeReturn__fn__fn__fn__opPutByIdSlow_LowLevelInterpreter_asm_655 18 0x136238cb4 17 ??? 0x0000000136238cb4 0x0 + 5203266740 19 0x12ea89c7c op_call_return_location 20 0x12ea89c7c op_call_return_location 21 0x12ea6075c llint_call_javascript 22 0x12d96013c JSC::Interpreter::executeProgram(JSC::SourceCode const&, JSC::JSGlobalObject*, JSC::JSObject*) 23 0x12dcb9410 JSC::evaluate(JSC::JSGlobalObject*, JSC::SourceCode const&, JSC::JSValue, WTF::NakedPtr<JSC::Exception>&) 24 0x12dcb9564 JSC::profiledEvaluate(JSC::JSGlobalObject*, JSC::ProfilingReason, JSC::SourceCode const&, JSC::JSValue, WTF::NakedPtr<JSC::Exception>&) 25 0x304795324 WebCore::JSExecState::profiledEvaluate(JSC::JSGlobalObject*, JSC::ProfilingReason, JSC::SourceCode const&, JSC::JSValue, WTF::NakedPtr<JSC::Exception>&) 26 0x304794d50 WebCore::ScriptController::evaluateInWorld(WebCore::ScriptSourceCode const&, WebCore::DOMWrapperWorld&) 27 0x304794a94 WebCore::ScriptController::evaluateInWorldIgnoringException(WebCore::ScriptSourceCode const&, WebCore::DOMWrapperWorld&) 28 0x30479516c WebCore::ScriptController::evaluateIgnoringException(WebCore::ScriptSourceCode const&) 29 0x30573a6c0 WebCore::ScriptElement::executeClassicScript(WebCore::ScriptSourceCode const&) 30 0x305738220 WebCore::ScriptElement::prepareScript(WTF::TextPosition const&) 31 0x305e3d864 WebCore::HTMLScriptRunner::runScript(WebCore::ScriptElement&, WTF::TextPosition const&) com.apple.WebKit.WebContent.Development terminated (pid 12889) for reason: crash **** Just raising, so we can track it and fix it. Thanks!