Fix routing in frontend not working (#723)

agent/pkg/routes/not_found_route.go

@@ -1,18 +0,0 @@
-package routes
-
-import (
-	"github.com/gin-gonic/gin"
-	"net/http"
-)
-
-// NotFoundRoute defines the 404 Error route.
-func NotFoundRoute(app *gin.Engine) {
-	app.Use(
-		func(c *gin.Context) {
-			c.JSON(http.StatusNotFound, map[string]interface{}{
-				"error": true,
-				"msg":   "sorry, endpoint is not found",
-			})
-		},
-	)
-}