send unknown routes to the react router

app/controllers/static_controller.rb

@@ -13,5 +13,7 @@ class StaticController < ActionController::API
   def frontend_static
     full_path = "protected_public/#{params[:path]}.#{params[:format]}"
     send_file full_path
+  rescue ActionController::MissingFile
+    render file: 'protected_public/index.html'
   end
 end