It seems to be an undefined variable.

似乎是个未定义的变数。

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。

Your code includes some undefined variable that you have used as if it was already defined and initialized.

你的代码包括一些未定义的变量，你作为已经定义并初始化的来使用。

There are plenty of Undefined Variable errors for variables and functions that should be present from the script, but other than that, no errors.

对于应该从脚本中出现的变量和函数，有大量未定义的变量错误，但除此之外，没有错误。

If you look at the Debug Messages pane, the answer is spelled out: The variable $multipler is undefined because it's a typo. It should be $multiplier.

如果看一下 Debug Messages 面板，答案就清楚了：变量 $multipler 是未定义的，因为它是一个拼写错误，应该是 $multiplier。