Clean up.

src/sphinx_autodoc_typehints/__init__.py

@@ -27,7 +27,7 @@
 if TYPE_CHECKING:
     from ast import FunctionDef, Module, stmt
 
-    from docutils.nodes import Node, document
+    from docutils.nodes import Node
     from docutils.parsers.rst import states
     from sphinx.application import Sphinx
     from sphinx.config import Config
@@ -823,13 +823,13 @@ def get_insert_index(app: Sphinx, lines: list[str]) -> InsertIndexInfo | None:
         # If there is a next sibling but we can't locate a line number, insert
         # at end. (I don't know of any input where this happens.)
         next_sibling = child.next_node(descend=False, siblings=True)
-        line_no = node_line_no(next_sibling)
+        line_no = node_line_no(next_sibling) if next_sibling else None
         at = line_no - 2 if line_no else len(lines)
         return InsertIndexInfo(insert_index=at, found_param=True)
 
     # 4. Insert before examples
     for child in doc.children:
-        if tag_name(child) in {"literal_block", "paragraph", "field_list", "substitution_definition"}:
+        if tag_name(child) in {"literal_block", "paragraph", "field_list"}:
             continue
         line_no = node_line_no(child)
         at = line_no - 2 if line_no else len(lines)