Add a message for _log.exception()

Otherwise it complains about the required positional argument

Author: hsinfang

python/activator/activator.py

@@ -348,7 +348,7 @@ def next_visit_handler() -> tuple[str, int]:
         try:
             expected_visit = parse_next_visit(flask.request)
         except ValueError as msg:
-            _log.exception()
+            _log.exception(msg)
             return f"Bad Request: {msg}", 400
         process_visit(expected_visit)
         return "Pipeline executed", 200
@@ -524,7 +524,7 @@ def process_visit(expected_visit: FannedOutVisit):
 
 
 def invalid_visit(e: InvalidVisitError) -> tuple[str, int]:
-    _log.exception()
+    _log.exception("Invalid visit: %s", e)
     return f"Cannot process visit: {e}.", 422