Fix session variable name

undercover/routes.py

@@ -162,7 +162,7 @@ def index_post():
             body=form.body.data,
         )
 
-        email = session.get('login')
+        email = session.get('username')
         if email:
             user = db.get_user(email)
             letters = db.get_user_letters(user.id)