diff --git a/nixie/cli.py b/nixie/cli.py
index fb4df86..e560bfc 100644
--- a/nixie/cli.py
+++ b/nixie/cli.py
@@ -22,7 +22,6 @@
 import shutil
 import sys
 import tempfile
-import traceback
 import typing
 from contextlib import contextmanager
 from pathlib import Path
@@ -108,7 +107,7 @@ async def wait_for_proc(
     """Wait for a process to complete and return its success status and stderr."""
     try:
         _, stderr = await asyncio.wait_for(proc.communicate(), timeout)
-    except asyncio.TimeoutError:
+    except TimeoutError:
         proc.kill()
         await proc.wait()
         print(f"{path}: diagram {idx} timed out", file=sys.stderr)
@@ -212,16 +211,11 @@ async def render_block(
     except FileNotFoundError as exc:
         cli = exc.filename or "mmdc"
         print(
-            "Error: '{0}' not found. Install Node.js with npx or Bun to use @mermaid-js/mermaid-cli.".format(
-                cli
-            ),
+            f"Error: '{cli}' not found. Install Node.js with npx or Bun to use @mermaid-js/mermaid-cli.",
             file=sys.stderr,
         )
     except RuntimeError as exc:
         print(exc, file=sys.stderr)
-    except Exception as exc:
-        print(f"{path}: unexpected error in diagram {idx}", file=sys.stderr)
-        traceback.print_exception(type(exc), exc, exc.__traceback__, file=sys.stderr)
     else:
         return True
     return False
diff --git a/nixie/unittests/test_render_diagram.py b/nixie/unittests/test_render_diagram.py
index 1e5d21f..be58b83 100644
--- a/nixie/unittests/test_render_diagram.py
+++ b/nixie/unittests/test_render_diagram.py
@@ -1,5 +1,4 @@
 from __future__ import annotations
-
 import asyncio
 import logging
 import shlex