fix: disable sso login when no issuer present

src/auth.ts

@@ -2,7 +2,9 @@ import NextAuth from 'next-auth';
 import Authentik from 'next-auth/providers/authentik';
 
 export const { handlers, signIn, signOut, auth } = NextAuth({
-  providers: [Authentik],
+  providers: [process.env.AUTH_AUTHENTIK_ISSUER ? Authentik : null].filter(
+    (x) => x !== null,
+  ),
   callbacks: {
     authorized: async ({ auth }) => {
       return !!auth;