Tokens may contain NULL. They must be :Data, not :Text

user.capnp

@@ -109,7 +109,7 @@ struct User
         # this frequently will force the server to store large amounts of data. 
         # Trying to bind a new key to an existing URL will fail.
 
-        unbind @3 ( token :Text ) -> ();
+        unbind @3 ( token :Data ) -> ();
         # Unbind the key associated with the given token. This will fail all future attempts to use
         # the card with the associated key.
     }