A fallback default HTTP error handler that can be used when there's no application available.
Note: this HttpErrorHandler uses the default HttpErrorConfig, which does not showDevErrors. It is largely here to preserve binary compatibility, but should be overridden with an injected HttpErrorHandler.
By default, the implementation of this method delegates to onProdServerError when in prod mode, and onDevServerError in dev mode. It is recommended, if you want Play's debug info on the error page in dev mode, that you override onProdServerError instead of this method.