simdata/_DataDir: report which exactly key is missing

1 files changed, 1 insertions, 1 deletions

diff --git a/simdata.py b/simdata.py
index ad42d0a..2464cb2 100644
--- a/simdata.py
+++ b/simdata.py
@@ -101,7 +101,7 @@ class _DataDir(MutableMapping):
 
     def __getitem__(self, key):
         if not key in self._paths:
-            raise KeyError
+            raise KeyError(key)
         elif self._files[key] is None:
             self._files[key] = datafile.DataFile(self._paths[key])