fix(core): ignore basePath if pages configuration (#10288)

* fix: pages configuration

* fix: typo

* chore: test custom pages config

---------

Co-authored-by: Thang Vu <hi@thvu.dev>

packages/core/src/index.ts

@@ -183,8 +183,9 @@ export async function Auth(
     if (error instanceof CredentialsSignin) params.set("code", error.code)
 
     const pageKind = (isAuthError && error.kind) || "error"
-    const pagePath = config.pages?.[pageKind] ?? `/${pageKind.toLowerCase()}`
-    const url = `${internalRequest.url.origin}${config.basePath}${pagePath}?${params}`
+    const pagePath =
+      config.pages?.[pageKind] ?? `${config.basePath}/${pageKind.toLowerCase()}`
+    const url = `${internalRequest.url.origin}${pagePath}?${params}`
 
     if (isRedirect) return Response.json({ url })
     return Response.redirect(url)

packages/core/test/actions/callback.test.ts

@@ -3,6 +3,7 @@ import * as jose from "jose"
 import * as o from "oauth4webapi"
 
 import GitHub from "../../src/providers/github.js"
+import Credentials from "../../src/providers/credentials.js"
 
 import { makeAuthRequest } from "../utils.js"
 
@@ -66,3 +67,21 @@ describe("assert GET callback action", () => {
     )
   })
 })
+
+it("should redirect to the custom error page is custom error page is defined", async () => {
+  const { response } = await makeAuthRequest({
+    action: "callback",
+    path: "/credentials",
+    config: {
+      pages: {
+        error:'/custom/error'
+      },
+      providers: [Credentials],
+    },
+  })
+
+  expect(response.status).toEqual(302)
+  expect(response.headers.get("location")).toEqual(
+    `https://authjs.test/custom/error?error=Configuration`
+  )
+})