Fire click event on run only once Pyodide loads

[jvfe]

• Simple hack to avoid / fix Update demo editor "Run" button to be deactivated until Pyodide finishes loading #197
• Expands the logic in the click events to check for the existence of the window.instance object before firing the event.
• Also fixes a typo I saw
• Test it here

[berinhard]

Thanks for catching the typo too!

[berinhard]

@jvfe and thanks for using github's fix thing. It really helps because it automatically closes the related issue.