Do not lose cause of exception

Author: maartenbreddels

nbclient/util.py

@@ -41,7 +41,7 @@ def wrapped(self, *args, **kwargs):
                     'You are trying to run nbclient in an environment where an '
                     'event loop is already running. Please pass `nest_asyncio=True` in '
                     '`NotebookClient.execute` and such methods.'
-                )
+                ) from e
             raise
         return result
     wrapped.__doc__ = coro.__doc__