Preserve exception chain in morsel_to_cookie max-age conversion

src/requests/cookies.py

@@ -496,8 +496,8 @@ def morsel_to_cookie(morsel):
     if morsel["max-age"]:
         try:
             expires = int(time.time() + int(morsel["max-age"]))
-        except ValueError:
-            raise TypeError(f"max-age: {morsel['max-age']} must be integer")
+        except ValueError as exc:
+            raise TypeError(f"max-age: {morsel['max-age']} must be integer") from exc
     elif morsel["expires"]:
         time_template = "%a, %d-%b-%Y %H:%M:%S GMT"
         expires = calendar.timegm(time.strptime(morsel["expires"], time_template))

tests/test_requests.py

@@ -2479,6 +2479,22 @@ def test_max_age_invalid_str(self):
         with pytest.raises(TypeError):
             morsel_to_cookie(morsel)
 
+    def test_max_age_exception_chaining(self):
+        """Test that exception chaining is preserved when max-age conversion fails."""
+
+        morsel = Morsel()
+        morsel["max-age"] = "invalid"
+        with pytest.raises(TypeError) as exc_info:
+            morsel_to_cookie(morsel)
+
+        # Verify the TypeError was raised
+        assert "max-age: invalid must be integer" in str(exc_info.value)
+
+        # Verify the original ValueError is preserved as the cause
+        assert exc_info.value.__cause__ is not None
+        assert isinstance(exc_info.value.__cause__, ValueError)
+        assert "invalid literal for int()" in str(exc_info.value.__cause__)
+
 
 class TestTimeout:
     def test_stream_timeout(self, httpbin):