Instead of checking for a default compound value, you can also catch the access to an undefined variable. E.g.

不用再检查默认的复合值，您也可以捕获对未定义变量的访问。

youdao

It seems to be an undefined variable.

似乎是个未定义的变数。

youdao

It seems to be an undefined variable.

似乎是个未定义的变数。

youdao