plugin XEP-0363: fixed invalid reference to `slot` in catched exception: `slot` was referenced in an exception where it can't exist. This fix avoid a crash and skip the handler when a StanzaError is catched.

# XXX: the Monkey Patch is here and not in src/__init__ to avoir issues with pyjamas compilation
# TODO: remove this when changes are merged in Wokkel
from sat_tmp.wokkel import install
install()