Problem about 'undefined' is null

[sai]

If I use wpi to chang the option , if always pop up the error message

it says :Message : 'undefined' is null or not a object

But, if i chang the useroption.js with notepad, it is ok !

Why ? Who cah tell me why ?

What should I do?

Thank u very much

[Kelsenellenelvian]

Which option/s are you changing?