By default your .jscad file is parsed in a separate thread (in a Web Worker). This allows long running
scripts to be executed while the web browser stays responsive. The web browser's debugger does not
have access to scripts running in web workers however. To allow debugging you can use the Debug button above to execute
your jscad code in the main thread instead of in a web worker.
To debug your code in Google Chrome: open the Developer Tools by typing Ctrl+Shift+I (or Command+Option+I on mac).
Then press the Debug button above. The debugger will stop just before executing your main() function.