factor out 404 handler so all 404s are the same

process/handlers.go

@@ -88,6 +88,10 @@ func (a *Server) getInstanceListHandler() http.HandlerFunc {
 }
 */
 
+func (a *Server) notFoundHandler(c echo.Context) error {
+	return c.String(http.StatusNotFound, "404 not found")
+}
+
 func (a *Server) instanceHandler(c echo.Context) error {
 	tu := c.Param("uuid")
 	u, err := uuid.Parse(tu)
@@ -103,6 +107,12 @@ func (a *Server) instanceHandler(c echo.Context) error {
 		}
 	}
 
+	_, exists := tc["instance"]
+
+	if !exists {
+		return a.notFoundHandler(c)
+	}
+
 	return c.Render(http.StatusOK, "instance.html", tc)
 }