ICNS format: QImageReader::setAllocationLimit() bug

Hi,

Since a recent update to Qt 6.6 I'm having issues loading ICNS files when the allocation limit is disabled. Here is a test code loading an ICNS file with allocation limit disabled and saving it as JPEG:

#include <QCoreApplication>
#include <QImageReader>
#include <QFileInfo>

int main(int argc, char *argv[]) {

    QCoreApplication a(argc, argv);

    QString filename = "/path/to/sample.icns";

    QImageReader reader(filename);

    reader.setAllocationLimit(0);

    QImage img;
    reader.read(&img);

    img.save("/path/to/sample.jpg");

    return 0;
}

I also attaches a sample.icns file I used in my testing. When I run the above code as is with the allocation limit set to 0, then I get this error message and no resulting jpeg file:

maximum memory limit (0) would be exceeded
Jasper thread initialization failed
QICNSHandler::read(): Failed, compressed format "jp2" is not supported by your Qt library or this file is corrupt. OSType: "ic08"

If I change the allocation limit to something greater than 0 (or remove it altogether), then the above error message disappears and the file is successfully saved as jpeg file.

I tested some other file types and the behavior of QImageReader was as expected, I only observed this issue with ICNS files.