fix: reformat markdown filter files and fix stale MathDelimiterProblem attribute

black --check was failing on markdown.py and test_markdown_filter.py,
which were never reformatted after being added. That masked a second
bug: _warn_markdown_issues still read problem.value, left over from
before check_markdown() started returning MathDelimiterProblem
dataclasses (f08f4df) instead of bare MathDelimiterError enums.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

Author: m-messer

in2lambda/filters/markdown.py

@@ -164,9 +164,11 @@ def markdown_converter(
                 except Exception:
                     expression = elem.text
                 return pf.RawInline(
-                    f"${expression}$"
-                    if elem.format == "InlineMath"
-                    else f"\n\n$$\n{expression}\n$$\n\n",
+                    (
+                        f"${expression}$"
+                        if elem.format == "InlineMath"
+                        else f"\n\n$$\n{expression}\n$$\n\n"
+                    ),
                     format="markdown",
                 )
 

in2lambda/main.py

@@ -22,7 +22,7 @@
 def _warn_markdown_issues(text: str, source: str) -> None:
     """Echo a warning for each math-delimiter problem found in a markdown source."""
     for problem in check_markdown(text):
-        click.echo(f"Warning: {source}: {problem.value}")
+        click.echo(f"Warning: {source}: {problem}")
 
 
 def docx_to_md(docx_file: str) -> str:

tests/test_markdown_filter.py

@@ -24,7 +24,9 @@ def test_example_parses_into_questions_parts_and_solutions(filters_dir: str) ->
         "How long does the ball take to reach the ground, using:\n\n"
         "- the vertical motion equation\n- the given height and gravity"
     )
-    assert projectile.parts[1].text == "How far from the launch point does the ball land?"
+    assert (
+        projectile.parts[1].text == "How far from the launch point does the ball land?"
+    )
     assert projectile.parts[0].worked_solution.startswith("Vertical motion is")
     # The ``---`` separator survives as a literal step boundary.
     assert "\n\n---\n\n" in projectile.parts[0].worked_solution