Fix code example

[Horttcore]

No description provided.

[Jean85]

This is correct, thanks for spotting this! Registering the handler though is not enough, thanks to #762 (and #788 in the future); so, to make the example complete, you should add the listener registration.

[ste93cry]

Since I'm evaluating in #788 to stop registering implicitly the error handler in the ErrorHandler::add*Listener methods (and so make them non-static), to be future-proof I would change the example to something similar to

$errorHandler = ErrorHandler::registerOnce();
$errorHandler->addErrorListener(...);
$errorHandler->addFatalErrorListener(...);
$errorHandler->addExceptionListener(...);

[ste93cry]

The PR I was talking about has been merged, but the changes will be available only from version 2.1. Since the UPGRADE-2.0.md is targeting of course the 2.0 version it seems to me that the changes here are fine as they are except for the fact that as said by @Jean85 we should document that at least a listener should be added to report the errors. @Horttcore are you willing to address the requested changes so that we can merge this PR?

[stayallive]

I am closing this PR because of inactivity, I even believe this problem was eventually addressed.