NodeJs and express help?

I was built authentication feature in my app but my deserialize part in code is not working.
It gives me this


Hey there,

please do not post screenshots of your errors.

Instead please copy the code and put it into the “Preformatted text” tool </>.

Without seeing your code, the only action to help you is reading and typing your error into a search engine, so please upload it somewhere, e.g. on glitch or