notification_endpoint is null error

[dorsaffer]

Getting an error when running the solid webhook demo
To reproduce ;
Run the CSS in memory fs mode
Register for a new pod,
Click the login and then Create document
Click Subscribe and the error is thrown

The subscribe endpoint code looks like this

app.get("/subscribe", async (req, res) => {
  const authSession = await getAuthSession(req);
  console.log(authSession);
  try{ 
    const { unsubscribeEndpoint } = await subscribe(
    `${POD_ORIGIN}${RESOURCE_CONTAINER}`,
    `${LOCAL_ORIGIN}/webhook`,
    { fetch: authSession.fetch })
    unsubscribeUris.push(unsubscribeEndpoint);
  }catch(error){
    console.log(error);

  }
  console.log("Subscribed to Resource");
  renderDashboard(res);
});

The undefinable value in the error is the notification_endpoint URL, I checked the notification config and everything looks okay

{
      "comment": "The WellKnown Builder for base notifications",
      "@id": "urn:solid-server:default:BaseNotificationWellKnownBuilder",
      "@type": "NotificationWellKnownBuilder",
      "args_baseUrl": { "@id": "urn:solid-server:default:variable:baseUrl" },
      "args_notificationEndpointPath": "gateway"
    },

If it helps this is the configuration that I used for the demo application example:

const PORT = 3001;
const LOCAL_ORIGIN = `http://localhost:${PORT}`;
const POD_ORIGIN = `http://localhost:3000`;
const RESOURCE_NAME = "test.ttl";
const RESOURCE_CONTAINER = "/webhookPod/profile/";
const RESOURCE_PATH = `${RESOURCE_CONTAINER}${RESOURCE_NAME}`;

[jaxoncreed]

This library only works with the experimental webhook implementation in this pull request: CommunitySolidServer/CommunitySolidServer#1080. A vanilla version of CSS will not work with it. Also, note that webhooks on Solid are very experimental and will change in the future.