lanqsh

A nullptr can lead to `Segmentation fault`

1

https://github.com/qinguoyi/TinyWebServer/blob/7e103e82375d316403dbc0ea25d2feca7a2146b6/http/http_conn.cpp?_pjax=%23js-repo-pjax-container%2C%20div%5Bitemtype%3D%22http%3A%2F%2Fschema.org%2FSoftwareSourceCode%22%5D%20main%2C%20%5Bdata-pjax-container%5D#L24 if mysql connect err,will this ptr be NULL? fix it will be great