What is the Yarn update effects on custom code?

I am facing the issue that my JS changes are not showing on UI then I ran the bench build command, and I got the yarn update error. i attached the screenshot also.

So, I have 2 questions.
First, what are the commands to update the yarn? And do we really need to update the yarn to show the JS changes on the UI?
and second, is yarn update will effect the custom code?



Please check the installation.