Mongodb – I keep getting TypeError: Cannot read properties of undefined (reading 'length') and I can't seem to find the source of the error

const userRegistrationPost = (req, res) => {
    const{name, email, pass1, pass2} = req.body;

        let errors = [];

        if(!name|| !email || !pass1 || !pass2){
            errors.push({msg: "Please ensure all fields are filled"});
        }

        if(pass1 !==pass2){
            errors.push({msg: "Passwords don't match"});
        }
        
        if(pass1.length < 6){   //line 66
            errors.push({msg: "Passwords must be at least 6 characters"});
        }

        if(errors.length > 0){
            res.render("user_registration", {errors, name, email, pass1, pass2})
        }else{
        //WE DON'T WANT TO HAVE 2 USERS WITH THE SAME EMAIL
            User.findOne({email: email})
            .then((result)=> {
                if(result){
                    errors.push({msg: "Email already exists"});
                    res.render("user_registration", errors, name, email, pass1, pass2)
                }else{
                    //HERE WE TRY TO ENCRYPT OUR PASSWORD
                    bcrypt.hash(pass1, 10, (error, hash)=>{
                        const nUser = new User({
                            name, email, password: hash,
                        })
                        try{
                            nUser.save();
                            req.flash('message', "Registration Successful. You can now Signup")
                            res.redirect('/user_login');
                        }
                        catch(err){
                            req.flash('error_msg', "Could not save into the Database");
                            res.redirect('user_registration');
                        }
                    })
                }
            })
            .catch((err)=> {
                res.send("There's a problem");
                console.log(err);
            })
        }
}

It says the error occurs on line 66. It was supposed to save users into the database after inputing their details but it keeps giving me TypeError.