Add route not found and default message for QuestionService API

Author: qiaoen17

Backend/QuestionService/app.js

@@ -17,4 +17,27 @@ mongoose.connect(mongoURI)
 
 app.use('/api/questions', questionRouter)
 
+app.get("/", (req, res, next) => {
+    console.log("Sending Greetings!");
+    res.json({
+      message: "Hello World from question-service",
+    });
+  });
+  
+// Handle When No Route Match Is Found
+app.use((req, res, next) => {
+    const error = new Error("Route Not Found");
+    error.status = 404;
+    next(error);
+});
+
+app.use((error, req, res, next) => {
+    res.status(error.status || 500);
+    res.json({
+      error: {
+        message: error.message,
+      },
+    });
+});
+
 module.exports = app