Fix a bug where null pointers were not judged

[Andrew12138-w]

1. 这个PR修复的是什么问题？ 对于可能为空的指针，没有进行提前的判断，判断的逻辑错误 2. 这个PR不修复具体会带来什么后果？ 可能会导致指针错误，程序崩溃，非法访存等问题 3. PR修复方案的依据是什么？ 延照原函数的流程顺序，在不改变程序流向与函数返回结果的前提下，将空指针判断提前进行，保证了程序的可靠和安全 4. 在什么环境下测试或者验证过？ all

[tencent-adm]

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