Robot JS SDK User Guide

Hello, I am new here and need help please. I am following Robot JS SDK User Guide to create localhost server to use a sample web app from “Boilerplate Sample” to run my automation. I am using http://127.0.0.1:8000, but simple web app gives below error. Please help, thank you in advance!
Browser Embedding Sample Application

Something else went wrong Error: Illegal characters in path.
​​​​​​​
Process List
Browser Embedding Sample with Arguments
Refresh Robot Process Download sample with arguments
Name
string value
Surname
string value
Age
int value
Subscription
True