After added chat prosody plugin "mod_muc_chat_recording.lua" chat not working

I want to save the chatHistory on my local pc. After surfing I found the prosody plugin called “mod_muc_chat_recording.lua”. I have configured it with my site.cfg.lua. Then restarted the prosody and launched to chat section but the chat is not working, it’s throwing the following error. I am new to jitsi and lua script. Could any one help plz.

mod_bosh error Traceback[bosh]: …re/jitsi-meet/prosody-plugins/mod_muc_chat_recording.lua:40: attempt to index field ‘?’ (a nil value)
stack traceback:
…re/jitsi-meet/prosody-plugins/mod_muc_chat_recording.lua:40: in function ‘extractMessage’
…re/jitsi-meet/prosody-plugins/mod_muc_chat_recording.lua:81: in function ‘?’
/usr/lib/prosody/util/events.lua:79: in function </usr/lib/prosody/util/events.lua:75>
(…tail calls…)
/usr/lib/prosody/core/stanza_router.lua:180: in function ‘core_post_stanza’
/usr/lib/prosody/core/stanza_router.lua:127: in function ‘dispatch_stanza’
/usr/lib/prosody/modules/mod_bosh.lua:323: in function ‘func’
/usr/lib/prosody/util/async.lua:127: in function </usr/lib/prosody/util/async.lua:125>
stack traceback:
/usr/lib/prosody/util/async.lua:211: in function ‘run’
/usr/lib/prosody/modules/mod_bosh.lua:465: in function ‘cb_handlestanza’
/usr/lib/prosody/util/xmppstream.lua:182: in function </usr/lib/prosody/util/xmppstream.lua:162>
[C]: in function ‘parse’
/usr/lib/prosody/util/xmppstream.lua:285: in function ‘feed’
/usr/lib/prosody/modules/mod_bosh.lua:134: in function ‘?’
/usr/lib/prosody/util/events.lua:79: in function </usr/lib/prosody/util/events.lua:75>
(…tail calls…)
/usr/lib/prosody/net/http/server.lua:229: in function </usr/lib/prosody/net/http/server.lua:176>
[C]: in function ‘xpcall’
/usr/lib/prosody/net/http/server.lua:108: in function ‘process_next’
/usr/lib/prosody/net/http/server.lua:124: in function ‘success_cb’
/usr/lib/prosody/net/http/parser.lua:177: in function ‘feed’
/usr/lib/prosody/net/http/server.lua:155: in function </usr/lib/prosody/net/http/server.lua:154>
(…tail calls…)
/usr/lib/prosody/net/server_select.lua:924: in function </usr/lib/prosody/net/server_select.lua:908>
[C]: in function ‘xpcall’
/usr/bin/prosody:76: in function ‘loop’
/usr/bin/prosody:86: in main chunk
[C]: in ?