Found while fuzzing m-c 20221203-d17c3b5d62f0 (--enable-debug --enable-fuzzing)

To reproduce via Grizzly Replay:

$ pip install fuzzfetch grizzly-framework
$ python -m fuzzfetch -d --fuzzing -n firefox
$ python -m grizzly.replay ./firefox/firefox testcase.html

Assertion failure: !HasCaretPointSuggestion() || CaretPointHandled(), at /builds/worker/checkouts/gecko/editor/libeditor/HTMLEditHelpers.h:461

#0 0x7f6e8815be78 in mozilla::SplitNodeResult::~SplitNodeResult() /builds/worker/checkouts/gecko/editor/libeditor/HTMLEditHelpers.h:461:5
#1 0x7f6e881f3296 in ~ResultImplementationNullIsOk /builds/worker/workspace/obj-build/dist/include/mozilla/Result.h:183:37
#2 0x7f6e881f3296 in ~Result /builds/worker/workspace/obj-build/dist/include/mozilla/Result.h:478:21
#3 0x7f6e881f3296 in mozilla::HTMLEditor::SplitRangeOffFromBlock(mozilla::dom::Element&, nsIContent&, nsIContent&) /builds/worker/checkouts/gecko/editor/libeditor/HTMLEditSubActionHandler.cpp:5929:1
#4 0x7f6e881f1cb3 in mozilla::HTMLEditor::OutdentPartOfBlock(mozilla::dom::Element&, nsIContent&, nsIContent&, mozilla::HTMLEditor::BlockIndentedWith, mozilla::dom::Element const&) /builds/worker/checkouts/gecko/editor/libeditor/HTMLEditSubActionHandler.cpp:5938:7
#5 0x7f6e881f137c in mozilla::HTMLEditor::HandleOutdentAtSelectionInternal(mozilla::dom::Element const&) /builds/worker/checkouts/gecko/editor/libeditor/HTMLEditSubActionHandler.cpp:5783:7
#6 0x7f6e881ee581 in mozilla::HTMLEditor::HandleOutdentAtSelection(mozilla::dom::Element const&) /builds/worker/checkouts/gecko/editor/libeditor/HTMLEditSubActionHandler.cpp:5272:7
#7 0x7f6e881ee095 in mozilla::HTMLEditor::OutdentAsSubAction(mozilla::dom::Element const&) /builds/worker/checkouts/gecko/editor/libeditor/HTMLEditSubActionHandler.cpp:5213:7
#8 0x7f6e88217bd5 in mozilla::HTMLEditor::OutdentAsAction(nsIPrincipal*) /builds/worker/checkouts/gecko/editor/libeditor/HTMLEditor.cpp:2881:47
#9 0x7f6e88233cdc in mozilla::OutdentCommand::DoCommand(mozilla::Command, mozilla::EditorBase&, nsIPrincipal*) const /builds/worker/checkouts/gecko/editor/libeditor/HTMLEditorCommands.cpp:444:44
#10 0x7f6e84993736 in mozilla::dom::Document::ExecCommand(nsTSubstring<char16_t> const&, bool, nsTSubstring<char16_t> const&, nsIPrincipal&, mozilla::ErrorResult&) /builds/worker/checkouts/gecko/dom/base/Document.cpp:5491:37
#11 0x7f6e85d5918f in mozilla::dom::Document_Binding::execCommand(JSContext*, JS::Handle<JSObject*>, void*, JSJitMethodCallArgs const&) /builds/worker/workspace/obj-build/dom/bindings/DocumentBinding.cpp:4149:36
#12 0x7f6e860ee912 in bool mozilla::dom::binding_detail::GenericMethod<mozilla::dom::binding_detail::NormalThisPolicy, mozilla::dom::binding_detail::ThrowExceptions>(JSContext*, unsigned int, JS::Value*) /builds/worker/checkouts/gecko/dom/bindings/BindingUtils.cpp:3308:13
#13 0x7f6e8a5012a6 in CallJSNative(JSContext*, bool (*)(JSContext*, unsigned int, JS::Value*), js::CallReason, JS::CallArgs const&) /builds/worker/checkouts/gecko/js/src/vm/Interpreter.cpp:459:13
#14 0x7f6e8a500bcf in js::InternalCallOrConstruct(JSContext*, JS::CallArgs const&, js::MaybeConstruct, js::CallReason) /builds/worker/checkouts/gecko/js/src/vm/Interpreter.cpp:547:12
#15 0x7f6e8a4f280f in CallFromStack /builds/worker/checkouts/gecko/js/src/vm/Interpreter.cpp:619:10
#16 0x7f6e8a4f280f in Interpret(JSContext*, js::RunState&) /builds/worker/checkouts/gecko/js/src/vm/Interpreter.cpp:3362:16
#17 0x7f6e8a4e5ece in js::RunScript(JSContext*, js::RunState&) /builds/worker/checkouts/gecko/js/src/vm/Interpreter.cpp:431:13
#18 0x7f6e8a500acb in js::InternalCallOrConstruct(JSContext*, JS::CallArgs const&, js::MaybeConstruct, js::CallReason) /builds/worker/checkouts/gecko/js/src/vm/Interpreter.cpp:579:13
#19 0x7f6e8a501ffc in js::Call(JSContext*, JS::Handle<JS::Value>, JS::Handle<JS::Value>, js::AnyInvokeArgs const&, JS::MutableHandle<JS::Value>, js::CallReason) /builds/worker/checkouts/gecko/js/src/vm/Interpreter.cpp:646:8
#20 0x7f6e8a5be45c in JS::Call(JSContext*, JS::Handle<JS::Value>, JS::Handle<JS::Value>, JS::HandleValueArray const&, JS::MutableHandle<JS::Value>) /builds/worker/checkouts/gecko/js/src/vm/CallAndConstruct.cpp:117:10
#21 0x7f6e85dc3073 in mozilla::dom::EventListener::HandleEvent(mozilla::dom::BindingCallContext&, JS::Handle<JS::Value>, mozilla::dom::Event&, mozilla::ErrorResult&) /builds/worker/workspace/obj-build/dom/bindings/EventListenerBinding.cpp:62:8
#22 0x7f6e866e6336 in void mozilla::dom::EventListener::HandleEvent<mozilla::dom::EventTarget*>(mozilla::dom::EventTarget* const&, mozilla::dom::Event&, mozilla::ErrorResult&, char const*, mozilla::dom::CallbackObject::ExceptionHandling, JS::Realm*) /builds/worker/workspace/obj-build/dist/include/mozilla/dom/EventListenerBinding.h:65:12
#23 0x7f6e866e605c in mozilla::EventListenerManager::HandleEventSubType(mozilla::EventListenerManager::Listener*, mozilla::dom::Event*, mozilla::dom::EventTarget*) /builds/worker/checkouts/gecko/dom/events/EventListenerManager.cpp:1308:43
#24 0x7f6e866e6d09 in mozilla::EventListenerManager::HandleEventInternal(nsPresContext*, mozilla::WidgetEvent*, mozilla::dom::Event**, mozilla::dom::EventTarget*, nsEventStatus*, bool) /builds/worker/checkouts/gecko/dom/events/EventListenerManager.cpp:1504:17
#25 0x7f6e866dbb76 in HandleEvent /builds/worker/checkouts/gecko/dom/events/EventListenerManager.h:395:5
#26 0x7f6e866dbb76 in mozilla::EventTargetChainItem::HandleEvent(mozilla::EventChainPostVisitor&, mozilla::ELMCreationDetector&) /builds/worker/checkouts/gecko/dom/events/EventDispatcher.cpp:347:17
#27 0x7f6e866db277 in mozilla::EventTargetChainItem::HandleEventTargetChain(nsTArray<mozilla::EventTargetChainItem>&, mozilla::EventChainPostVisitor&, mozilla::EventDispatchingCallback*, mozilla::ELMCreationDetector&) /builds/worker/checkouts/gecko/dom/events/EventDispatcher.cpp:585:14
#28 0x7f6e866dd865 in mozilla::EventDispatcher::Dispatch(nsISupports*, nsPresContext*, mozilla::WidgetEvent*, mozilla::dom::Event*, nsEventStatus*, mozilla::EventDispatchingCallback*, nsTArray<mozilla::dom::EventTarget*>*) /builds/worker/checkouts/gecko/dom/events/EventDispatcher.cpp:1122:11
#29 0x7f6e866e0416 in mozilla::EventDispatcher::DispatchDOMEvent(nsISupports*, mozilla::WidgetEvent*, mozilla::dom::Event*, nsPresContext*, nsEventStatus*) /builds/worker/checkouts/gecko/dom/events/EventDispatcher.cpp
#30 0x7f6e84c247eb in nsINode::DispatchEvent(mozilla::dom::Event&, mozilla::dom::CallerType, mozilla::ErrorResult&) /builds/worker/checkouts/gecko/dom/base/nsINode.cpp:1373:17
#31 0x7f6e866ed772 in mozilla::dom::EventTarget::DispatchEvent(mozilla::dom::Event&) /builds/worker/checkouts/gecko/dom/events/EventTarget.cpp:180:13
#32 0x7f6e8669b7cb in mozilla::AsyncEventDispatcher::Run() /builds/worker/checkouts/gecko/dom/events/AsyncEventDispatcher.cpp:69:12
#33 0x7f6e8477746f in nsContentUtils::RemoveScriptBlocker() /builds/worker/checkouts/gecko/dom/base/nsContentUtils.cpp:5951:17
#34 0x7f6e849a5bec in mozilla::dom::Document::EndUpdate() /builds/worker/checkouts/gecko/dom/base/Document.cpp:7825:3
#35 0x7f6e849fc29d in ~mozAutoDocUpdate /builds/worker/checkouts/gecko/dom/base/mozAutoDocUpdate.h:34:18
#36 0x7f6e849fc29d in mozilla::dom::Element::SetAttr(int, nsAtom*, nsAtom*, nsTSubstring<char16_t> const&, nsIPrincipal*, bool) /builds/worker/checkouts/gecko/dom/base/Element.cpp:2488:1
#37 0x7f6e849fbd4f in SetAttr /builds/worker/workspace/obj-build/dist/include/mozilla/dom/Element.h:959:12
#38 0x7f6e849fbd4f in mozilla::dom::Element::SetAttribute(nsTSubstring<char16_t> const&, nsTSubstring<char16_t> const&, nsIPrincipal*, mozilla::ErrorResult&) /builds/worker/checkouts/gecko/dom/base/Element.cpp:1514:14
#39 0x7f6e85ded612 in mozilla::dom::Element_Binding::setAttribute(JSContext*, JS::Handle<JSObject*>, void*, JSJitMethodCallArgs const&) /builds/worker/workspace/obj-build/dom/bindings/ElementBinding.cpp:1812:24
#40 0x7f6e860ee912 in bool mozilla::dom::binding_detail::GenericMethod<mozilla::dom::binding_detail::NormalThisPolicy, mozilla::dom::binding_detail::ThrowExceptions>(JSContext*, unsigned int, JS::Value*) /builds/worker/checkouts/gecko/dom/bindings/BindingUtils.cpp:3308:13
#41 0x7f6e8a5012a6 in CallJSNative(JSContext*, bool (*)(JSContext*, unsigned int, JS::Value*), js::CallReason, JS::CallArgs const&) /builds/worker/checkouts/gecko/js/src/vm/Interpreter.cpp:459:13
#42 0x7f6e8a500bcf in js::InternalCallOrConstruct(JSContext*, JS::CallArgs const&, js::MaybeConstruct, js::CallReason) /builds/worker/checkouts/gecko/js/src/vm/Interpreter.cpp:547:12
#43 0x7f6e8a4f280f in CallFromStack /builds/worker/checkouts/gecko/js/src/vm/Interpreter.cpp:619:10
#44 0x7f6e8a4f280f in Interpret(JSContext*, js::RunState&) /builds/worker/checkouts/gecko/js/src/vm/Interpreter.cpp:3362:16
#45 0x7f6e8a4e5ece in js::RunScript(JSContext*, js::RunState&) /builds/worker/checkouts/gecko/js/src/vm/Interpreter.cpp:431:13
#46 0x7f6e8a500acb in js::InternalCallOrConstruct(JSContext*, JS::CallArgs const&, js::MaybeConstruct, js::CallReason) /builds/worker/checkouts/gecko/js/src/vm/Interpreter.cpp:579:13
#47 0x7f6e8a501ffc in js::Call(JSContext*, JS::Handle<JS::Value>, JS::Handle<JS::Value>, js::AnyInvokeArgs const&, JS::MutableHandle<JS::Value>, js::CallReason) /builds/worker/checkouts/gecko/js/src/vm/Interpreter.cpp:646:8
#48 0x7f6e8a5be45c in JS::Call(JSContext*, JS::Handle<JS::Value>, JS::Handle<JS::Value>, JS::HandleValueArray const&, JS::MutableHandle<JS::Value>) /builds/worker/checkouts/gecko/js/src/vm/CallAndConstruct.cpp:117:10
#49 0x7f6e85dc05d1 in mozilla::dom::EventHandlerNonNull::Call(mozilla::dom::BindingCallContext&, JS::Handle<JS::Value>, mozilla::dom::Event&, JS::MutableHandle<JS::Value>, mozilla::ErrorResult&) /builds/worker/workspace/obj-build/dom/bindings/EventHandlerBinding.cpp:65:37
#50 0x7f6e86706529 in void mozilla::dom::EventHandlerNonNull::Call<nsCOMPtr<mozilla::dom::EventTarget>>(nsCOMPtr<mozilla::dom::EventTarget> const&, mozilla::dom::Event&, JS::MutableHandle<JS::Value>, mozilla::ErrorResult&, char const*, mozilla::dom::CallbackObject::ExceptionHandling, JS::Realm*) /builds/worker/workspace/obj-build/dist/include/mozilla/dom/EventHandlerBinding.h:82:12
#51 0x7f6e86705716 in mozilla::JSEventHandler::HandleEvent(mozilla::dom::Event*) /builds/worker/checkouts/gecko/dom/events/JSEventHandler.cpp:199:12
#52 0x7f6e866e609d in mozilla::EventListenerManager::HandleEventSubType(mozilla::EventListenerManager::Listener*, mozilla::dom::Event*, mozilla::dom::EventTarget*) /builds/worker/checkouts/gecko/dom/events/EventListenerManager.cpp:1314:22
#53 0x7f6e866e6d09 in mozilla::EventListenerManager::HandleEventInternal(nsPresContext*, mozilla::WidgetEvent*, mozilla::dom::Event**, mozilla::dom::EventTarget*, nsEventStatus*, bool) /builds/worker/checkouts/gecko/dom/events/EventListenerManager.cpp:1504:17
#54 0x7f6e866dbb76 in HandleEvent /builds/worker/checkouts/gecko/dom/events/EventListenerManager.h:395:5
#55 0x7f6e866dbb76 in mozilla::EventTargetChainItem::HandleEvent(mozilla::EventChainPostVisitor&, mozilla::ELMCreationDetector&) /builds/worker/checkouts/gecko/dom/events/EventDispatcher.cpp:347:17
#56 0x7f6e866db0ab in mozilla::EventTargetChainItem::HandleEventTargetChain(nsTArray<mozilla::EventTargetChainItem>&, mozilla::EventChainPostVisitor&, mozilla::EventDispatchingCallback*, mozilla::ELMCreationDetector&) /builds/worker/checkouts/gecko/dom/events/EventDispatcher.cpp:549:16
#57 0x7f6e866dd865 in mozilla::EventDispatcher::Dispatch(nsISupports*, nsPresContext*, mozilla::WidgetEvent*, mozilla::dom::Event*, nsEventStatus*, mozilla::EventDispatchingCallback*, nsTArray<mozilla::dom::EventTarget*>*) /builds/worker/checkouts/gecko/dom/events/EventDispatcher.cpp:1122:11
#58 0x7f6e8848da64 in nsDocumentViewer::LoadComplete(nsresult) /builds/worker/checkouts/gecko/layout/base/nsDocumentViewer.cpp:1079:7
#59 0x7f6e89ace580 in nsDocShell::EndPageLoad(nsIWebProgress*, nsIChannel*, nsresult) /builds/worker/checkouts/gecko/docshell/base/nsDocShell.cpp:6447:20
#60 0x7f6e89acdb2b in nsDocShell::OnStateChange(nsIWebProgress*, nsIRequest*, unsigned int, nsresult) /builds/worker/checkouts/gecko/docshell/base/nsDocShell.cpp:5840:7
#61 0x7f6e89acf426 in non-virtual thunk to nsDocShell::OnStateChange(nsIWebProgress*, nsIRequest*, unsigned int, nsresult) /builds/worker/checkouts/gecko/docshell/base/nsDocShell.cpp
#62 0x7f6e83e61988 in nsDocLoader::DoFireOnStateChange(nsIWebProgress*, nsIRequest*, int&, nsresult) /builds/worker/checkouts/gecko/uriloader/base/nsDocLoader.cpp:1380:3
#63 0x7f6e83e60f72 in nsDocLoader::doStopDocumentLoad(nsIRequest*, nsresult) /builds/worker/checkouts/gecko/uriloader/base/nsDocLoader.cpp:978:14
#64 0x7f6e83e5f205 in nsDocLoader::DocLoaderIsEmpty(bool, mozilla::Maybe<nsresult> const&) /builds/worker/checkouts/gecko/uriloader/base/nsDocLoader.cpp:797:9
#65 0x7f6e83e60405 in nsDocLoader::OnStopRequest(nsIRequest*, nsresult) /builds/worker/checkouts/gecko/uriloader/base/nsDocLoader.cpp:680:5
#66 0x7f6e89b0145e in nsDocShell::OnStopRequest(nsIRequest*, nsresult) /builds/worker/checkouts/gecko/docshell/base/nsDocShell.cpp:13866:23
#67 0x7f6e8314685f in mozilla::net::nsLoadGroup::NotifyRemovalObservers(nsIRequest*, nsresult) /builds/worker/checkouts/gecko/netwerk/base/nsLoadGroup.cpp:628:22
#68 0x7f6e83147d83 in mozilla::net::nsLoadGroup::RemoveRequest(nsIRequest*, nsISupports*, nsresult) /builds/worker/checkouts/gecko/netwerk/base/nsLoadGroup.cpp:532:10
#69 0x7f6e849bfb89 in mozilla::dom::Document::DoUnblockOnload() /builds/worker/checkouts/gecko/dom/base/Document.cpp:11552:18
#70 0x7f6e84a404be in mozilla::dom::nsUnblockOnloadEvent::Run() /builds/worker/checkouts/gecko/dom/base/Document.cpp:11514:11
#71 0x7f6e82f33d82 in mozilla::SchedulerGroup::Runnable::Run() /builds/worker/checkouts/gecko/xpcom/threads/SchedulerGroup.cpp:114:20
#72 0x7f6e82f3e015 in mozilla::RunnableTask::Run() /builds/worker/checkouts/gecko/xpcom/threads/TaskController.cpp:539:16
#73 0x7f6e82f395ec in mozilla::TaskController::DoExecuteNextTaskOnlyMainThreadInternal(mozilla::detail::BaseAutoLock<mozilla::Mutex&> const&) /builds/worker/checkouts/gecko/xpcom/threads/TaskController.cpp:852:26
#74 0x7f6e82f381ba in mozilla::TaskController::ExecuteNextTaskOnlyMainThreadInternal(mozilla::detail::BaseAutoLock<mozilla::Mutex&> const&) /builds/worker/checkouts/gecko/xpcom/threads/TaskController.cpp:684:15
#75 0x7f6e82f38515 in mozilla::TaskController::ProcessPendingMTTask(bool) /builds/worker/checkouts/gecko/xpcom/threads/TaskController.cpp:462:36
#76 0x7f6e82f41916 in operator() /builds/worker/checkouts/gecko/xpcom/threads/TaskController.cpp:188:37
#77 0x7f6e82f41916 in mozilla::detail::RunnableFunction<mozilla::TaskController::InitializeInternal()::$_2>::Run() /builds/worker/workspace/obj-build/dist/include/nsThreadUtils.h:546:5
#78 0x7f6e82f56e15 in nsThread::ProcessNextEvent(bool, bool*) /builds/worker/checkouts/gecko/xpcom/threads/nsThread.cpp:1197:16
#79 0x7f6e82f5d13d in NS_ProcessNextEvent(nsIThread*, bool) /builds/worker/checkouts/gecko/xpcom/threads/nsThreadUtils.cpp:477:10
#80 0x7f6e83b56163 in mozilla::ipc::MessagePump::Run(base::MessagePump::Delegate*) /builds/worker/checkouts/gecko/ipc/glue/MessagePump.cpp:85:21
#81 0x7f6e83a77f18 in MessageLoop::RunInternal() /builds/worker/checkouts/gecko/ipc/chromium/src/base/message_loop.cc:381:10
#82 0x7f6e83a77e21 in RunHandler /builds/worker/checkouts/gecko/ipc/chromium/src/base/message_loop.cc:374:3
#83 0x7f6e83a77e21 in MessageLoop::Run() /builds/worker/checkouts/gecko/ipc/chromium/src/base/message_loop.cc:356:3
#84 0x7f6e880779d8 in nsBaseAppShell::Run() /builds/worker/checkouts/gecko/widget/nsBaseAppShell.cpp:148:27
#85 0x7f6e8a2bb6bb in XRE_RunAppShell() /builds/worker/checkouts/gecko/toolkit/xre/nsEmbedFunctions.cpp:742:20
#86 0x7f6e83b57029 in mozilla::ipc::MessagePumpForChildProcess::Run(base::MessagePump::Delegate*) /builds/worker/checkouts/gecko/ipc/glue/MessagePump.cpp:235:9
#87 0x7f6e83a77f18 in MessageLoop::RunInternal() /builds/worker/checkouts/gecko/ipc/chromium/src/base/message_loop.cc:381:10
#88 0x7f6e83a77e21 in RunHandler /builds/worker/checkouts/gecko/ipc/chromium/src/base/message_loop.cc:374:3
#89 0x7f6e83a77e21 in MessageLoop::Run() /builds/worker/checkouts/gecko/ipc/chromium/src/base/message_loop.cc:356:3
#90 0x7f6e8a2bb218 in XRE_InitChildProcess(int, char**, XREChildData const*) /builds/worker/checkouts/gecko/toolkit/xre/nsEmbedFunctions.cpp:675:34
#91 0x555c61a07ce0 in content_process_main /builds/worker/checkouts/gecko/browser/app/../../ipc/contentproc/plugin-container.cpp:57:28
#92 0x555c61a07ce0 in main /builds/worker/checkouts/gecko/browser/app/nsBrowserApp.cpp:359:18
#93 0x7f6e9667bd8f in __libc_start_call_main csu/../sysdeps/nptl/libc_start_call_main.h:58:16
#94 0x7f6e9667be3f in __libc_start_main csu/../csu/libc-start.c:392:3
#95 0x555c619de348 in _start (/home/user/workspace/browsers/m-c-20230120212103-fuzzing-debug/firefox-bin+0x5b348) (BuildId: fb2ab566cecf57e47d9c81989c8a405fb904864f)

Verified bug as reproducible on mozilla-central 20230124213422-ba77054848c4.
The bug appears to have been introduced in the following build range:

Start: 53d6e1b0d2c3c86f55666a2a5ac8be1587ae750d (20221003012405)
End: f36d9e78e41726fe8cd299e04b7fad07d208ec79 (20221003110443)
Pushlog: https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=53d6e1b0d2c3c86f55666a2a5ac8be1587ae750d&tochange=f36d9e78e41726fe8cd299e04b7fad07d208ec79

Set release status flags based on info from the regressing bug 1792639

A caller, HTMLEditor::SplitRangeOffFromBlock, cannot unwrap it for ignoring
non-critical errors. Therefore, MoveCaretPointTo is not available and
instead, CopyCaretPointTo is used. However, calling it is not treated as
"handled. Therefore, it detects forgetting to handle the point at destruction.
Copying the point means that the caller handles it even though the source is
not cleared. Therefore, a call of it should be treated as "handled".

Depends on D167778

https://hg.mozilla.org/mozilla-central/rev/cc7737d0048c

Verified bug as fixed on rev mozilla-central 20230201215112-b7f075124503.
Removing bugmon keyword as no further action possible. Please review the bug and re-add the keyword for further analysis.