Using popup mode from local file causes misleading error

[nicosabena]

When trying to use popup mode from a local html file (file:///.../sample.html), authentication appears to work correctly, but the popup window remains open, with message "Login was successful Please close this tab to continue".

When closing the popup, a server error is reported by the callback, originated from https://github.com/auth0/auth0.js/blob/master/lib/LoginError.js#L31. When debugging, this is actually called from the popup window (xxx.auth0.com/login/callback) with the message "User closed the popup window".
So, first problem is that we get a "Server error" when the error is cause by "User closed the popup window". But there is another problem before: the automatic window closing fails, reporting an invalid origin (null value) with stack trace:

Uncaught SyntaxError: Failed to execute 'postMessage' on 'Window': Invalid target origin 'null' in a call to 'postMessage'.
doPost @ callback?state=Q9IE2CiZcZxavVqD&code=4/8rmDyM5lhQ17h2BW1QKoB6UHVmHXAZbI39hPwTNp3PU:394
(anonymous function) @ callback?state=Q9IE2CiZcZxavVqD&code=4/8rmDyM5lhQ17h2BW1QKoB6UHVmHXAZbI39hPwTNp3PU:416
resolve @ callback?state=Q9IE2CiZcZxavVqD&code=4/8rmDyM5lhQ17h2BW1QKoB6UHVmHXAZbI39hPwTNp3PU:117
(anonymous function) @ callback:521(anonymous function) @ callback?state=Q9IE2CiZcZxavVqD&code=4/8rmDyM5lhQ17h2BW1QKoB6UHVmHXAZbI39hPwTNp3PU:414

This is all probably cause by an invalid origin (the local file, file:///) but since is not properly handled the errors are very misleadings. When the file is served from a http server, there is a message correctly indicating an incorrect origin.