show_error_dialog.js

function showErrorDialog() {

    var errorOptions = {
        details: "This is simply the message that can be downloaded by clickick 'Download log file'",
        errorCode: 666, //this is error code if you want to show some specific one. If you specify invalid code or none, the default error code wouldbe displayed
        message: "Message show in the dialog"
    };

    Xrm.Navigation.openErrorDialog(errorOptions).then(
        success => {
            console.log("Dialog was closed successfully");
        },
        error => {
            console.log(error);
        });
}