From 912b50cfd574919c1086f0337c060bd1267da134 Mon Sep 17 00:00:00 2001
From: Stefan <96178532+stefan6419846@users.noreply.github.com>
Date: Sun, 9 Feb 2025 10:10:02 +0100
Subject: [PATCH] BUG: Handle annotations being None on merging (#3111)

Closes #3110.
---
 pypdf/_writer.py     |  4 +++-
 tests/test_writer.py | 11 +++++++++++
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/pypdf/_writer.py b/pypdf/_writer.py
index a67c270d4..9fb460b56 100644
--- a/pypdf/_writer.py
+++ b/pypdf/_writer.py
@@ -2932,7 +2932,7 @@ def _get_cloned_page(
 
     def _insert_filtered_annotations(
         self,
-        annots: Union[IndirectObject, List[DictionaryObject]],
+        annots: Union[IndirectObject, List[DictionaryObject], None],
         page: PageObject,
         pages: Dict[int, PageObject],
         reader: PdfReader,
@@ -2940,6 +2940,8 @@ def _insert_filtered_annotations(
         outlist = ArrayObject()
         if isinstance(annots, IndirectObject):
             annots = cast("List[Any]", annots.get_object())
+        if annots is None:
+            return outlist
         for an in annots:
             ano = cast("DictionaryObject", an.get_object())
             if (
diff --git a/tests/test_writer.py b/tests/test_writer.py
index fa8ffadef..939e2f847 100644
--- a/tests/test_writer.py
+++ b/tests/test_writer.py
@@ -2607,3 +2607,14 @@ def test_inline_image_q_operator_handling(tmp_path):
     )
     assert png_path.is_file()
     assert image_similarity(png_path, expected_png_path) >= 0.99999
+
+
+def test_insert_filtered_annotations__annotations_are_none():
+    writer = PdfWriter()
+    writer.add_blank_page(72, 72)
+    stream = BytesIO()
+    writer.write(stream)
+    reader = PdfReader(stream)
+    assert writer._insert_filtered_annotations(
+        annots=None, page=PageObject(), pages={}, reader=reader
+    ) == []