2020-04-10 08:40:15.077131 [NOTICE] mrcp_application.c:171 () Destroy MRCP Handle 0x7f090003c2e0
2020-04-10 08:40:15.077131 [CRIT] switch_cpp.cpp:1287 Result is 'nil'
2020-04-10 08:40:15.077131 [ERR] mod_lua.cpp:200 /usr/local/freeswitch/scripts/baidu.lua:49: attempt to concatenate global 'result' (a nil value)
stack traceback:
/usr/local/freeswitch/scripts/baidu.lua:49: in main chunk
2020-04-10 08:40:15.077131 [NOTICE] switch_core_state_machine.c:262 sofia/internal/8889@39.97.176.191 has executed the last dialplan instruction, hanging up.

主要参考的这个，https://ptorch.com/news/207.html，但现在出现这个错误，具体是什么问题？