[Click] Bug with click_chatter and %{element}

[Ruben Merz]

Hi,

I am using the following for debugging in some elements

click_chatter("%{element} blablabla", this);

This appears to crash with the latest HEAD from Click. I typically get 
this error

../lib/error.cc: 726: static String ErrorHandler::vxformat(int, const 
char*, char*): Assertion `0' failed.
Aborted

If anyone has any suggestion, thanks a lot in advance.
Ruben