The error I get:
Error: Cannot read properties of null (reading ‘name’)

<h1 className="text-4xl font-bold">Welcome {user.name}!</h1>

Expected result:

1. Delete access token
2. Regenerate the access token with the refresh token
3. const user populate

What seems to be happening:

1. Delete access token
2. const user populate
3. Regenerate the access token with the refresh token

In short words, the variable is getting populated before the token is re-generated.
Infact if you refresh the page it gets populated.

How can I fix it?

I’m using Next.js 14.2.4

import {getUser} from "@/utils/user";

const Admin = () => {
  const user = getUser() ;

  return (
    
    <section className="container">
        <h1 className="text-4xl font-bold">Welcome {user.name}!</h1>      
    </section>
  );
};


export default Admin;

user.ts

import { cookies } from "next/headers";
import { jwtDecode } from "jwt-decode";

interface User {
  userId: number;
  name: string;
  email: string;
  iat: number;
  exp: number;
}

export  function getUser(): User | null {
  const token = cookies().get("accessToken")?.value;  
  if (token) {
    try {
      return jwtDecode(token);
    } catch (error) {
      console.error("Failed to decode token:", error);
      return null;
    }
  }
  
  return null;
}

Middleware

import { NextResponse } from "next/server";
import type { NextRequest } from "next/server";
import { SignJWT, jwtVerify, type JWTPayload } from "jose";

async function refreshAccessToken(refreshToken: string) {
  const isRefreshTokenValid = await jwtVerify(refreshToken, new TextEncoder().encode(process.env.JWT_REFRESH_SECRET));


  if (isRefreshTokenValid) {
    const { id, name, email } = isRefreshTokenValid.payload;
    const payload = { id, name, email };
    const jwt = await new SignJWT(payload)
      .setProtectedHeader({ alg: "HS256" })
      .setIssuedAt()
      .setExpirationTime("15m")
      .sign(new TextEncoder().encode(process.env.JWT_SECRET));

    const response = NextResponse.next();

    response.cookies.set({
      name: "accessToken",
      value: jwt,
      maxAge: 60 * 15,
    });

    return response;
  }

  return NextResponse.redirect("http://localhost:3000/login");
}

export async function middleware(request: NextRequest) {
  const accessToken = request.cookies.get("accessToken")?.value;
  const refreshToken = request.cookies.get("refreshToken")?.value;

  if (accessToken) {
    const isAccessTokenValid = await jwtVerify(accessToken, new TextEncoder().encode(process.env.JWT_SECRET));
    return isAccessTokenValid ? NextResponse.next() : NextResponse.redirect("http://localhost:3000/login");
  }

  if (refreshToken) {
    return refreshAccessToken(refreshToken);
  }

  return NextResponse.redirect("http://localhost:3000/login");
}

export const config = {
  matcher: "/admin/",
};