fix #4063: Sphinx crushes when there are referenced todolist

CHANGES

@@ -28,6 +28,7 @@ Bugs fixed
 * #4070, #4111: crashes when the warning message contains format strings (again)
 * #4108: Search word highlighting breaks SVG images
 * #3692: Unable to build HTML if writing .buildinfo failed
+* #4063: Sphinx crashes when labelling directive '.. todolist::'
 
 Testing
 --------

sphinx/ext/todo.py

@@ -138,10 +138,10 @@ def process_todo_nodes(app, doctree, fromdocname):
 
     for node in doctree.traverse(todolist):
         if not app.config['todo_include_todos']:
-            node.replace_self([])
+            node.replace_self([nodes.target()])
             continue
 
-        content = []
+        content = [nodes.target()]
 
         for todo_info in env.todo_all_todos:  # type: ignore
             para = nodes.paragraph(classes=['todo-source'])