[nil] utils.item_to_string

[LaurenceJJones]

function above can return nil if the value is not an ip address this causes a nil concatenation in some cases.

2025/10/02 20:47:47 [info] 68873#68873: *1 [lua] crowdsec_nginx.conf:28):5: Initializing stream mode for worker 0, context: init_worker_by_lua*
2025/10/02 20:47:47 [info] 68873#68873: *1 [lua] crowdsec_nginx.conf:28):10: Initializing metrics for worker 0, context: init_worker_by_lua*
2025/10/02 20:47:47 [info] 68876#68876: *2 [lua] crowdsec_nginx.conf:28):5: Initializing stream mode for worker 3, context: init_worker_by_lua*
2025/10/02 20:47:47 [info] 68874#68874: *3 [lua] crowdsec_nginx.conf:28):5: Initializing stream mode for worker 1, context: init_worker_by_lua*
2025/10/02 20:47:47 [info] 68875#68875: *4 [lua] crowdsec_nginx.conf:28):5: Initializing stream mode for worker 2, context: init_worker_by_lua*
2025/10/02 20:47:53 [error] 68873#68873: *20 lua entry thread aborted: runtime error: /usr/lib/crowdsec/lua/plugins/crowdsec/stream.lua:221: attempt to concatenate local 'ip_type' (a nil value)
stack traceback:
coroutine 0:
        /usr/lib/crowdsec/lua/plugins/crowdsec/stream.lua: in function 'stream_query'
        /usr/lib/crowdsec/lua/crowdsec.lua:332: in function </usr/lib/crowdsec/lua/crowdsec.lua:314>, context: ngx.timer