mod_limit_auth errors out with [s2s] traceback

[variablenix]

I recently loaded the _limitauth module and just today noticed frequent traceback log entries.

Sep 23 21:13:54 mod_s2s error   Traceback[s2s]: /usr/lib/prosody/modules/mod_limit_auth.lua:30: table index is nil
stack traceback:
    /usr/lib/prosody/modules/mod_limit_auth.lua:30: in function 'get_throttle'
    /usr/lib/prosody/modules/mod_limit_auth.lua:37: in function '?'
    /usr/lib/prosody/util/events.lua:67: in function 'fire_event'
    /usr/lib/prosody/core/stanza_router.lua:149: in function 
    (tail call): ?
    [C]: in function 'xpcall'
    /usr/lib/prosody/modules/mod_s2s/mod_s2s.lua:445: in function 'cb_handlestanza'
    /usr/lib/prosody/util/xmppstream.lua:187: in function 
    [C]: in function 'parse'
    /usr/lib/prosody/util/xmppstream.lua:255: in function 'feed'
    /usr/lib/prosody/modules/mod_s2s/mod_s2s.lua:545: in function 'data'
    /usr/lib/prosody/modules/mod_s2s/mod_s2s.lua:605: in function 'onincoming'
    /usr/lib/prosody/net/server_event.lua:632: in function 
    [C]: in function 'loop'
    /usr/lib/prosody/net/server_event.lua:793: in function 
    [C]: in function 'xpcall'
    /usr/lib/prosody/../../bin/prosody:376: in function 'loop'
    /usr/lib/prosody/../../bin/prosody:407: in main chunk
    [C]: ?

I don't think this is the issue, but I looked over my prosody.cfg and only have these module options set.

limit_auth_period = 30 -- over 30 seconds limit_auth_max = 6 -- tolerate no more than 6 failed attempts

Prosody 0.9.8