What is causing this error?

Question

Information Security

What causes this error and can "evil uncles" use this error to hack the site?

Answer 1

What causes this error and can "evil uncles" use this error to hack the site?

Written almost in Russian - the most primitive mistake. There is no variable.
I think they can, if there are such simple mistakes on the site, but you can’t even understand them, then ...

Answer 2

written in black and white, undefined variable on line 304

Answer 3

You can just disable error reporting if it's that disturbing for you
error_reporting(0);