From 3a741edbf1432556dfe9e917cd129b0c847e78f3 Mon Sep 17 00:00:00 2001
From: Afonso Coutinho <afonso@omelhorsite.pt>
Date: Wed, 3 Jun 2026 06:06:35 +0100
Subject: [PATCH] fix: visual_report markdown helpers crash on a non-string
 input (#1633)

---
 src/visual_report.py                  |  4 ++++
 tests/test_visual_report_nonstring.py | 18 ++++++++++++++++++
 2 files changed, 22 insertions(+)
 create mode 100644 tests/test_visual_report_nonstring.py

diff --git a/src/visual_report.py b/src/visual_report.py
index fa021cd..007d0dd 100644
--- a/src/visual_report.py
+++ b/src/visual_report.py
@@ -37,6 +37,8 @@ def _autolink_urls(md_text: str) -> str:
 
     Skips URLs already inside markdown link syntax [text](url).
     """
+    if not isinstance(md_text, str):
+        return md_text
     # Match bare URLs not already inside ](...)
     return re.sub(
         r'(?<!\]\()(?<!\()(https?://[^\s\)<>]+)',
@@ -67,6 +69,8 @@ def _md_to_html(md_text: str) -> str:
 
 def _extract_headings(md_text: str) -> List[Dict[str, str]]:
     """Pull h2/h3 headings from markdown for table of contents."""
+    if not isinstance(md_text, str):
+        return []
     headings = []
     seen_slugs: Dict[str, int] = {}
 
diff --git a/tests/test_visual_report_nonstring.py b/tests/test_visual_report_nonstring.py
new file mode 100644
index 0000000..d4791f9
--- /dev/null
+++ b/tests/test_visual_report_nonstring.py
@@ -0,0 +1,18 @@
+"""Regression: visual_report markdown helpers must tolerate a non-string.
+
+_autolink_urls did `re.sub(..., md_text)` and _extract_headings did
+`re.finditer(..., md_text)`; a None/non-string raised TypeError. They now
+return the input / [] respectively.
+"""
+from src.visual_report import _autolink_urls, _extract_headings
+
+
+def test_non_string_does_not_crash():
+    assert _autolink_urls(None) is None
+    assert _extract_headings(None) == []
+    assert _extract_headings(123) == []
+
+
+def test_valid_markdown_unchanged():
+    assert "](https://x.com)" in _autolink_urls("see https://x.com")
+    assert _extract_headings("## Title")[0]["text"] == "Title"