--- a/editor/libeditor/HTMLEditRules.cpp
+++ b/editor/libeditor/HTMLEditRules.cpp
@@ -7690,48 +7690,60 @@ HTMLEditRules::SplitParagraph(
 
   // split para
   // get ws code to adjust any ws
   nsCOMPtr<nsINode> selNode = aStartOfRightNode.GetContainer();
   int32_t selOffset = aStartOfRightNode.Offset();
   nsresult rv =
     WSRunObject::PrepareToSplitAcrossBlocks(&HTMLEditorRef(),
                                             address_of(selNode), &selOffset);
+  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;
   }
 
   // Split the paragraph.
   SplitNodeResult splitDivOrPResult =
     HTMLEditorRef().SplitNodeDeepWithTransaction(
                       aParentDivOrP,
                       EditorRawDOMPoint(selNode, selOffset),
                       SplitAtEdges::eAllowToCreateEmptyContainer);
+  if (NS_WARN_IF(!CanHandleEditAction())) {
+    return NS_ERROR_EDITOR_DESTROYED;
+  }
   if (NS_WARN_IF(splitDivOrPResult.Failed())) {
     return splitDivOrPResult.Rv();
   }
   if (NS_WARN_IF(!splitDivOrPResult.DidSplit())) {
     return NS_ERROR_FAILURE;
   }
 
   // Get rid of the break, if it is visible (otherwise it may be needed to
   // prevent an empty p).
   if (aNextBRNode && HTMLEditorRef().IsVisibleBRElement(aNextBRNode)) {
     rv = HTMLEditorRef().DeleteNodeWithTransaction(*aNextBRNode);
+    if (NS_WARN_IF(!CanHandleEditAction())) {
+      return NS_ERROR_EDITOR_DESTROYED;
+    }
     if (NS_WARN_IF(NS_FAILED(rv))) {
       return rv;
     }
   }
 
   // Remove ID attribute on the paragraph from the existing right node.
   rv = HTMLEditorRef().RemoveAttributeWithTransaction(aParentDivOrP,
                                                       *nsGkAtoms::id);
+  if (NS_WARN_IF(!CanHandleEditAction())) {
+    return NS_ERROR_EDITOR_DESTROYED;
+  }
   if (NS_WARN_IF(NS_FAILED(rv))) {
     return rv;
   }
 
   // We need to ensure to both paragraphs visible even if they are empty.
   // However, moz-<br> element isn't useful in this case because moz-<br>
   // elements will be ignored by PlaintextSerializer.  Additionally,
   // moz-<br> will be exposed as <br> with Element.innerHTML.  Therefore,
@@ -7748,22 +7760,28 @@ HTMLEditRules::SplitParagraph(
 
   // selection to beginning of right hand para;
   // look inside any containers that are up front.
   nsIContent* child = HTMLEditorRef().GetLeftmostChild(&aParentDivOrP, true);
   if (EditorBase::IsTextNode(child) || HTMLEditorRef().IsContainer(child)) {
     EditorRawDOMPoint atStartOfChild(child, 0);
     IgnoredErrorResult ignoredError;
     SelectionRef().Collapse(atStartOfChild, ignoredError);
+    if (NS_WARN_IF(!CanHandleEditAction())) {
+      return NS_ERROR_EDITOR_DESTROYED;
+    }
     NS_WARNING_ASSERTION(!ignoredError.Failed(),
       "Failed to collapse selection at the end of the child");
   } else {
     EditorRawDOMPoint atChild(child);
     IgnoredErrorResult ignoredError;
     SelectionRef().Collapse(atChild, ignoredError);
+    if (NS_WARN_IF(!CanHandleEditAction())) {
+      return NS_ERROR_EDITOR_DESTROYED;
+    }
     NS_WARNING_ASSERTION(!ignoredError.Failed(),
       "Failed to collapse selection at the child");
   }
   return NS_OK;
 }
 
 nsresult
 HTMLEditRules::ReturnInListItem(Element& aListItem,

--- a/editor/libeditor/HTMLEditRules.h
+++ b/editor/libeditor/HTMLEditRules.h
@@ -392,19 +392,20 @@ protected:
    * @param aStartOfRightNode   The point to be start of right node after
    *                            split.  This must be descendant of
    *                            aParentDivOrP.
    * @param aNextBRNode         Next <br> node if there is.  Otherwise, nullptr.
    *                            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);
+  MOZ_MUST_USE nsresult
+  SplitParagraph(Element& aParentDivOrP,
+                 const EditorDOMPointBase<PT, CT>& aStartOfRightNode,
+                 nsIContent* aBRNode);
 
   /**
    * 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.