feat: add validators for username, email, password

* not passed yet

server/src/middleware/validator.js

@@ -0,0 +1,13 @@
+import { validationResult } from 'express-validator'
+
+export function noError(req, res, next) {
+  const result = validationResult(req)
+  if (result.isEmpty()) {
+    next()
+    return
+  }
+  console.log(result.array())
+  res.status(400).json({
+    errors: result.array(),
+  })
+}