Use a log file to write error log

docs/source/usage/graders/examples/addition.py

@@ -2,9 +2,13 @@
 
 import importlib.util
 import sys
+import traceback
 from collections.abc import Callable
+from pathlib import Path
 
 student_code_path: str = sys.argv[2]
+username: str = sys.argv[3]
+log_file = Path(sys.argv[4])
 
 test_cases = (
     (1, 2),
@@ -40,8 +44,9 @@ def import_module(modname: str = "student_submission", func_name="add_num") -> C
     try:
         spec.loader.exec_module(submission)
     except Exception:
-        # this traceback could provide sensitive information, so we don't provide it
+        # this traceback could provide sensitive information, so we don't provide it to students
         print("Could not test submission, an exception was raised while initializing.")
+        log_file.write_text(f"Student {username} import error:\n\n" + traceback.format_exc())
         # it's not our fault so we exit 0
         sys.exit(0)