This bug is for crash report bp-589804ce-4e85-4ed7-b7a0-58f8a0190605.

Top 10 frames of crashing thread:

0 libxul.so mozilla::EditorDOMPointBase<nsINode*, nsIContent*>& mozilla::EditorDOMPointBase<nsINode*, nsIContent*>::operator=<nsCOMPtr<nsINode>, nsCOMPtr<nsIContent> > editor/libeditor/EditorDOMPoint.h:589
1 libxul.so mozilla::WSRunObject::InsertText editor/libeditor/WSRunObject.cpp:382
2 libxul.so mozilla::HTMLEditRules::WillInsertText editor/libeditor/HTMLEditRules.cpp:1390
3 libxul.so mozilla::HTMLEditRules::WillDoAction editor/libeditor/HTMLEditRules.cpp:702
4 libxul.so mozilla::TextEditor::InsertTextAsSubAction editor/libeditor/TextEditor.cpp:1023
5 libxul.so mozilla::TextEditor::OnCompositionChange editor/libeditor/TextEditor.cpp:1353
6 libxul.so mozilla::EditorEventListener::HandleChangeComposition editor/libeditor/EditorEventListener.cpp:960
7 libxul.so mozilla::EditorEventListener::HandleEvent editor/libeditor/EditorEventListener.cpp:434
8 libxul.so mozilla::HTMLEditorEventListener::HandleEvent editor/libeditor/HTMLEditorEventListener.cpp:98
9 libxul.so mozilla::EventListenerManager::HandleEventSubType dom/events/EventListenerManager.cpp:1044

There are 4 crashes (from 4 installations) in 68.0b5 with buildid 20190527103257. In analyzing the backtrace, the regression may have been introduced by patch [1] to fix bug 1534394.

[1] https://hg.mozilla.org/releases/mozilla-beta/rev?node=54ff09f869d8

Looks like that this is dup of bug 1555640. The crash report does not have the patch.