"sendtext" example doesn't work

[tm-a-t]

Hi. I am hosting the example locally. When I click on "Send" button, its label changes to "Sending" and then nothing happens.
JS console output is the same as in the demo, but the demo works okay.
Am I doing something wrong?

UPD. Downloaded and ran the demo. It works ¯_(ツ)_/¯

When you say you downloaded the demo, where did you do so?