How to setup the local server?

Can anyone show a little testprogramm, working with the ServerConnection( "ws://localhost:3000" )? I dont get it to run :/

when i run it locally with npm start, i get:

microScript 2.0
{ error: 'Syntax Error', line: 735, column: 10, type: 'compile' }
{"name":"compile_success","file":"main"}
{
  error: 'Syntax Error',
  line: 735,
  column: 10,
  type: 'init',
  file: 'main'
}
{"name":"started"}

I think it still runs, I have to find out if it does tho

I mean the game server locally