Merge pull request #51 from ian-r-rose/fix_error_message

Conditionally use err.response.

Author: ian-r-rose

jupyterlab_github/__init__.py

@@ -103,7 +103,8 @@ def get(self, path=''):
 
         except HTTPError as err:
             self.set_status(err.code)
-            self.finish(err.response.body)
+            message = err.response.body if err.response else str(err.code)
+            self.finish(message)
 
     def _maybe_get_next_page_path(self, response):
         # If there is a 'Link' header in the response, we