Did the text response load or did clicking "Submit" do nothing? If you check the dev console (ctrl+shift+I in chrome) do you see any errors?
I'm not able to reproduce this error, unfortunately. If you're willing to try again and check the dev console I can probably fix it, but as of now I'm not sure what would cause this; perhaps something specific to your local environment.
There is a chance this was caused by errors that could previously occur when buttons were pressed while another function was executing. If so, the problem should be resolved now.