Refresh-Token JWT strategy

[TigMart]

import NextAuth, { type User } from "next-auth"
import Google from "next-auth/providers/google"
 
export const { handlers, auth } = NextAuth({
  providers: [
    Google({
      // Google requires "offline" access_type to provide a refresh_token
      authorization: { params: { access_type: "offline", prompt: "consent" } },
    }),
  ],
  callbacks: {
    async jwt({ token, account }) {
      if (account) {
        // First-time login, save the access_token, its expiry and the refresh_token
        return {
          ...token,
          access_token: account.access_token,
          expires_at: account.expires_at,
          refresh_token: account.refresh_token,
        }
      } else if (Date.now() < token.expires_at * 1000) {
        // Subsequent logins, but the access_token is still valid
        return token
      } else {
        // Subsequent logins, but the access_token has expired, try to refresh it
        if (!token.refresh_token) throw new TypeError("Missing refresh_token")
 
        try {
            const response = await fetch("https://oauth2.googleapis.com/token", {
            method: "POST",
            body: new URLSearchParams({
              client_id: process.env.AUTH_GOOGLE_ID!,
              client_secret: process.env.AUTH_GOOGLE_SECRET!,
              grant_type: "refresh_token",
              refresh_token: token.refresh_token!,
            }),
          })
 
          const tokensOrError = await response.json()
 
          if (!response.ok) throw tokensOrError
 
          const newTokens = tokensOrError as {
            access_token: string
            expires_in: number
            refresh_token?: string
          }
 
          token.access_token = newTokens.access_token
          token.expires_at = Math.floor(
            Date.now() / 1000 + newTokens.expires_in
          )

          if (newTokens.refresh_token)
            token.refresh_token = newTokens.refresh_token
          return token
        } catch (error) {
          console.error("Error refreshing access_token", error)
          token.error = "RefreshTokenError"
          return token
        }
      }
    },
  },
  session: ({ session, token }) => {
    session.error = token.error
    return session
  },
})
 
declare module "next-auth" {
  interface Session {
    error?: "RefreshTokenError"
  }
}
 
declare module "next-auth/jwt" {
  interface JWT {
    access_token: string
    expires_at: number
    refresh_token?: string
    error?: "RefreshTokenError"
  }
}

Maybe session should be in callbacks ?
session: ({ session, token }) => {
session.error = token.error
return session
},