Error out if error happens in fast import process

[gabyx]

I think this is a good behavior.
I added a slot for

    // Trigger a crictical error if any error in the process happens
    connect(this, &QProcess::errorOccurred, this,
        [this](QProcess::ProcessError error) {
            qCritical() << "Error happened in fast import process, error code: '" << error <<"'";
        });