--- a/editor/libeditor/HTMLEditRules.cpp
+++ b/editor/libeditor/HTMLEditRules.cpp
@@ -1928,18 +1928,24 @@ HTMLEditRules::WillInsertBreak(bool* aCa
                                                      endOfBlockParent);
     if (NS_WARN_IF(!brElement)) {
       return NS_ERROR_FAILURE;
     }
   }
 
   nsCOMPtr<Element> listItem = IsInListItem(blockParent);
   if (listItem && listItem != host) {
-    ReturnInListItem(*listItem, *atStartOfSelection.GetContainer(),
-                     atStartOfSelection.Offset());
+    nsresult rv =
+      ReturnInListItem(*listItem, *atStartOfSelection.GetContainer(),
+                       atStartOfSelection.Offset());
+    if (NS_WARN_IF(rv == NS_ERROR_EDITOR_DESTROYED)) {
+      return NS_ERROR_EDITOR_DESTROYED;
+    }
+    NS_WARNING_ASSERTION(NS_SUCCEEDED(rv),
+      "Failed to insert break into list item");
     *aHandled = true;
     return NS_OK;
   }
 
   if (HTMLEditUtils::IsHeader(*blockParent)) {
     // Headers: close (or split) header
     ReturnInHeader(*blockParent, *atStartOfSelection.GetContainer(),
                    atStartOfSelection.Offset());
@@ -7754,19 +7760,16 @@ HTMLEditRules::SplitParagraph(
     IgnoredErrorResult ignoredError;
     SelectionRef().Collapse(atChild, ignoredError);
     NS_WARNING_ASSERTION(!ignoredError.Failed(),
       "Failed to collapse selection at the child");
   }
   return NS_OK;
 }
 
-/**
- * ReturnInListItem: do the right thing for returns pressed in list items
- */
 nsresult
 HTMLEditRules::ReturnInListItem(Element& aListItem,
                                 nsINode& aNode,
                                 int32_t aOffset)
 {
   MOZ_ASSERT(IsEditorDataAvailable());
   MOZ_ASSERT(HTMLEditUtils::IsListItem(&aListItem));
 
@@ -7782,93 +7785,123 @@ HTMLEditRules::ReturnInListItem(Element&
     nsCOMPtr<nsIContent> leftListNode = aListItem.GetParent();
     // Are we the last list item in the list?
     if (!HTMLEditorRef().IsLastEditableChild(&aListItem)) {
       // We need to split the list!
       EditorRawDOMPoint atListItem(&aListItem);
       ErrorResult error;
       leftListNode =
         HTMLEditorRef().SplitNodeWithTransaction(atListItem, error);
+      if (NS_WARN_IF(!CanHandleEditAction())) {
+        error.SuppressException();
+        return NS_ERROR_EDITOR_DESTROYED;
+      }
       if (NS_WARN_IF(error.Failed())) {
         return error.StealNSResult();
       }
     }
 
     // Are we in a sublist?
     EditorRawDOMPoint atNextSiblingOfLeftList(leftListNode);
     DebugOnly<bool> advanced = atNextSiblingOfLeftList.AdvanceOffset();
     NS_WARNING_ASSERTION(advanced,
       "Failed to advance offset after the right list node");
     if (HTMLEditUtils::IsList(atNextSiblingOfLeftList.GetContainer())) {
       // If so, move item out of this list and into the grandparent list
       nsresult rv =
         HTMLEditorRef().MoveNodeWithTransaction(aListItem,
                                                 atNextSiblingOfLeftList);
+      if (NS_WARN_IF(!CanHandleEditAction())) {
+        return NS_ERROR_EDITOR_DESTROYED;
+      }
       if (NS_WARN_IF(NS_FAILED(rv))) {
         return rv;
       }
       ErrorResult error;
       SelectionRef().Collapse(RawRangeBoundary(&aListItem, 0), error);
+      if (NS_WARN_IF(!CanHandleEditAction())) {
+        error.SuppressException();
+        return NS_ERROR_EDITOR_DESTROYED;
+      }
       if (NS_WARN_IF(error.Failed())) {
         return error.StealNSResult();
       }
     } else {
       // Otherwise kill this item
       nsresult rv = HTMLEditorRef().DeleteNodeWithTransaction(aListItem);
+      if (NS_WARN_IF(!CanHandleEditAction())) {
+        return NS_ERROR_EDITOR_DESTROYED;
+      }
       if (NS_WARN_IF(NS_FAILED(rv))) {
         return rv;
       }
 
       // Time to insert a paragraph
       nsAtom& paraAtom = DefaultParagraphSeparator();
       // We want a wrapper even if we separate with <br>
       RefPtr<Element> pNode =
         HTMLEditorRef().CreateNodeWithTransaction(&paraAtom == nsGkAtoms::br ?
                                                     *nsGkAtoms::p : paraAtom,
                                                   atNextSiblingOfLeftList);
+      if (NS_WARN_IF(!CanHandleEditAction())) {
+        return NS_ERROR_EDITOR_DESTROYED;
+      }
       if (NS_WARN_IF(!pNode)) {
         return NS_ERROR_FAILURE;
       }
 
       // Append a <br> to it
       RefPtr<Element> brElement =
         HTMLEditorRef().InsertBrElementWithTransaction(
                           SelectionRef(), EditorRawDOMPoint(pNode, 0));
+      if (NS_WARN_IF(!CanHandleEditAction())) {
+        return NS_ERROR_EDITOR_DESTROYED;
+      }
       if (NS_WARN_IF(!brElement)) {
         return NS_ERROR_FAILURE;
       }
 
       // Set selection to before the break
       ErrorResult error;
       SelectionRef().Collapse(EditorRawDOMPoint(pNode, 0), error);
+      if (NS_WARN_IF(!CanHandleEditAction())) {
+        error.SuppressException();
+        return NS_ERROR_EDITOR_DESTROYED;
+      }
       if (NS_WARN_IF(error.Failed())) {
         return error.StealNSResult();
       }
     }
     return NS_OK;
   }
 
   // Else we want a new list item at the same list level.  Get ws code to
   // adjust any ws.
   nsCOMPtr<nsINode> selNode = &aNode;
   nsresult rv =
     WSRunObject::PrepareToSplitAcrossBlocks(&HTMLEditorRef(),
                                             address_of(selNode), &aOffset);
+  if (NS_WARN_IF(!CanHandleEditAction())) {
+    return NS_ERROR_EDITOR_DESTROYED;
+  }
   if (NS_WARN_IF(NS_FAILED(rv))) {
     return rv;
   }
   if (NS_WARN_IF(!selNode->IsContent())) {
     return NS_ERROR_FAILURE;
   }
 
   // Now split the list item.
   SplitNodeResult splitListItemResult =
     HTMLEditorRef().SplitNodeDeepWithTransaction(
                       aListItem, EditorRawDOMPoint(selNode, aOffset),
                       SplitAtEdges::eAllowToCreateEmptyContainer);
+  if (NS_WARN_IF(!CanHandleEditAction())) {
+    return NS_ERROR_EDITOR_DESTROYED;
+  }
   NS_WARNING_ASSERTION(splitListItemResult.Succeeded(),
     "Failed to split the list item");
 
   // Hack: until I can change the damaged doc range code back to being
   // extra-inclusive, I have to manually detect certain list items that may be
   // left empty.
   nsCOMPtr<nsIContent> prevItem =
     HTMLEditorRef().GetPriorHTMLSibling(&aListItem);
@@ -7898,46 +7931,63 @@ HTMLEditRules::ReturnInListItem(Element&
           nsAtom* listAtom = nodeAtom == nsGkAtoms::dt ? nsGkAtoms::dd
                                                         : nsGkAtoms::dt;
           MOZ_DIAGNOSTIC_ASSERT(itemOffset != -1);
           EditorRawDOMPoint atNextListItem(list, aListItem.GetNextSibling(),
                                            itemOffset + 1);
           RefPtr<Element> newListItem =
             HTMLEditorRef().CreateNodeWithTransaction(*listAtom,
                                                       atNextListItem);
+          if (NS_WARN_IF(!CanHandleEditAction())) {
+            return NS_ERROR_EDITOR_DESTROYED;
+          }
           if (NS_WARN_IF(!newListItem)) {
             return NS_ERROR_FAILURE;
           }
           rv = HTMLEditorRef().DeleteNodeWithTransaction(aListItem);
+          if (NS_WARN_IF(!CanHandleEditAction())) {
+            return NS_ERROR_EDITOR_DESTROYED;
+          }
           if (NS_WARN_IF(NS_FAILED(rv))) {
             return rv;
           }
           ErrorResult error;
           SelectionRef().Collapse(EditorRawDOMPoint(newListItem, 0), error);
+          if (NS_WARN_IF(!CanHandleEditAction())) {
+            error.SuppressException();
+            return NS_ERROR_EDITOR_DESTROYED;
+          }
           if (NS_WARN_IF(error.Failed())) {
             return error.StealNSResult();
           }
           return NS_OK;
         }
 
         RefPtr<Element> brElement;
         nsresult rv =
           HTMLEditorRef().CopyLastEditableChildStylesWithTransaction(
                             *prevItem->AsElement(), aListItem,
                             address_of(brElement));
+        if (NS_WARN_IF(!CanHandleEditAction())) {
+          return NS_ERROR_EDITOR_DESTROYED;
+        }
         if (NS_WARN_IF(NS_FAILED(rv))) {
           return NS_ERROR_FAILURE;
         }
         if (brElement) {
           EditorRawDOMPoint atBrNode(brElement);
           if (NS_WARN_IF(!atBrNode.IsSetAndValid())) {
             return NS_ERROR_FAILURE;
           }
           ErrorResult error;
           SelectionRef().Collapse(atBrNode, error);
+          if (NS_WARN_IF(!CanHandleEditAction())) {
+            error.SuppressException();
+            return NS_ERROR_EDITOR_DESTROYED;
+          }
           if (NS_WARN_IF(error.Failed())) {
             return error.StealNSResult();
           }
           return NS_OK;
         }
       } else {
         WSRunObject wsObj(&HTMLEditorRef(), &aListItem, 0);
         nsCOMPtr<nsINode> visNode;
@@ -7948,33 +7998,44 @@ HTMLEditRules::ReturnInListItem(Element&
         if (wsType == WSType::special || wsType == WSType::br ||
             visNode->IsHTMLElement(nsGkAtoms::hr)) {
           EditorRawDOMPoint atVisNode(visNode);
           if (NS_WARN_IF(!atVisNode.IsSetAndValid())) {
             return NS_ERROR_FAILURE;
           }
           ErrorResult error;
           SelectionRef().Collapse(atVisNode, error);
+          if (NS_WARN_IF(!CanHandleEditAction())) {
+            error.SuppressException();
+            return NS_ERROR_EDITOR_DESTROYED;
+          }
           if (NS_WARN_IF(error.Failed())) {
             return error.StealNSResult();
           }
           return NS_OK;
         }
 
         rv = SelectionRef().Collapse(visNode, visOffset);
+        if (NS_WARN_IF(!CanHandleEditAction())) {
+          return NS_ERROR_EDITOR_DESTROYED;
+        }
         if (NS_WARN_IF(NS_FAILED(rv))) {
           return rv;
         }
         return NS_OK;
       }
     }
   }
 
   ErrorResult error;
   SelectionRef().Collapse(EditorRawDOMPoint(&aListItem, 0), error);
+  if (NS_WARN_IF(!CanHandleEditAction())) {
+    error.SuppressException();
+    return NS_ERROR_EDITOR_DESTROYED;
+  }
   if (NS_WARN_IF(error.Failed())) {
     return error.StealNSResult();
   }
   return NS_OK;
 }
 
 nsresult
 HTMLEditRules::MakeBlockquote(nsTArray<OwningNonNull<nsINode>>& aNodeArray)

--- a/editor/libeditor/HTMLEditRules.h
+++ b/editor/libeditor/HTMLEditRules.h
@@ -396,17 +396,29 @@ protected:
    *                            If this is not nullptr, the <br> node may be
    *                            removed.
    */
   template<typename PT, typename CT>
   nsresult SplitParagraph(Element& aParentDivOrP,
                           const EditorDOMPointBase<PT, CT>& aStartOfRightNode,
                           nsIContent* aBRNode);
 
-  nsresult ReturnInListItem(Element& aHeader, nsINode& aNode, int32_t aOffset);
+  /**
+   * ReturnInListItem() handles insertParagraph command (i.e., handling
+   * Enter key press) in a list item element.
+   *
+   * @param aListItem           The list item which has the following point.
+   * @param aNode               Typically, Selection start container, where to
+   *                            insert a break.
+   * @param aOffset             Typically, Selection start offset in the
+   *                            start container, where to insert a break.
+   */
+  MOZ_MUST_USE nsresult
+  ReturnInListItem(Element& aListItem, nsINode& aNode, int32_t aOffset);
+
   nsresult AfterEditInner(EditAction action,
                           nsIEditor::EDirection aDirection);
   nsresult RemovePartOfBlock(Element& aBlock, nsIContent& aStartChild,
                              nsIContent& aEndChild);
   void SplitBlock(Element& aBlock,
                   nsIContent& aStartChild,
                   nsIContent& aEndChild,
                   nsIContent** aOutLeftNode = nullptr,