Can not serialize the debug backtrace?

[IngwiePhoenix]

OS 2.6.4-rc-x64 Copyright (C) 2012-2014 by Evgeniy Golovin
ObjectScript is free and open source: https://github.com/unitpoint/objectscript
> function f(){ print json.encode(debugBackTrace()); }
<function#2370>
> f()

Unhandled exception: 'DateTime 'this' must not be null'

#0 {{CORE}}: f, args: {}

When running OS remotely and using JSON as a layer of communication, this is rather problematic. How can I get the backtrace as JSON?