[Bug] Whitelist bug when deploy via apisix

What happened?

hello，

If you connect chaitin to apisix in a plug-in manner, add certain IPs to the whitelist, but check the option to record attack behaviors, as shown below:

访问接口，apisix会报500，去除勾选后正常。日志无记录。
chaitin版本lts 7.1.2

谢谢

How we reproduce?

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Expected behavior

No response

Error log

No response

apisix日志报错：[error] 51#51: *24653861 lua entry thread aborted: runtime error: /usr/local/apisix/apisix/plugins/chaitin-waf.lua:339: attempt to concatenate field 'event_id' (a nil value)

https://github.com/apache/apisix/pull/11651