How to stop routing to the given route if validation fails - node.js

Question

In my signup.ejs file, I have setup a form with post request and i have written /welcome route in signup.js file, I am trying to figure out how i can stop the post request to the given route if validation fails or how i can dynamically assign a different route like an error route (localhost:3000/signup/error instead of localhost:3000/signup/welcome if validation fails) as everytime signup fails, it is routing to localhost:3000/signup/welcome which is not right. I tried setting up variables in signup.ejs file to pass it in action, however, it only routes to /welcome and it doesn't route to /error. Basically, I just want to see error endpoint or just stop the POST request if validation fails. Please suggest.
signup.ejs
<h2>Sign Up</h2>
<% var route = ''; %>
<% if (!messages.error) { %>
<% route = '/welcome' %>
<% }else{ %>
<% route = '/error' %>
<% } %>
<form action="signup<%- route %>" method="post" name="form1">
signup.js
router.post('/welcome', function(req, res, next) {
req.checkBody('name', 'Name cannot be empty').notEmpty();
req.checkBody('email', 'Please enter valid email').isEmail();
req.checkBody('password', 'Password should be more than 5').isLength({ min: 5 });
req.checkBody('password1', 'Password do not match').equals(req.body.password);
var errors = req.validationErrors();
if(!errors) {
var user = {
name: req.sanitize('name').escape().trim(),
email: req.sanitize('email').escape().trim(),
password: req.sanitize('password').escape().trim()
}
connection.query('Insert into customers set ?', user, function(err, result) {
if(err) {
req.flash('error', err);
//render to signup
res.redirect('/signup', {
title: 'Add New User',
name: user.name,
email: user.email,
password: user.password
})
}
req.flash('success', 'Successfully signed up');
res.render('welcome', {
title: 'Signed In'
});
})
}else {
var error_msg = ''
errors.forEach(function(error) {
error_msg += error.msg + '<br>'
})
req.flash('error', error_msg);
res.render('signup', {
name: req.body.name,
email: req.body.email,
password: req.body.password
})
}
});