update test code snippets

Author: inventarSarah

platform-includes/getting-started-verify/javascript.connect.mdx

@@ -1,8 +1,8 @@
 First, let's make sure Sentry is correctly capturing errors and creating issues in your project. Add the following code snippet to your main application file; it defines a route that will deliberately trigger an error when called:
 
 ```javascript
-app.get("/debug-sentry", function mainHandler(req, res) {
-  throw new Error("My first Sentry error!");
+app.use("/debug-sentry", (req, res, next) => {
+  next(new Error("My first Sentry error!"));
 });
 ```
 
@@ -21,7 +21,7 @@ app.use("/debug-sentry", async (req, res, next) => {
       },
       async () => {
         await new Promise((resolve) => setTimeout(resolve, 100));
-        throw new Error("My first Sentry error!");
+        next(new Error("My first Sentry error!"));
       }
     );
   }