TypeError: OC_Image::getOrientation(): Return value must be of type int, array returned

Hello,

I'm running Nextcloud 26.0.11 and previewgenerator 5.4.0.

I am in the process of regenerating the image previews. Unfortunately I get this error:

TypeError: OC_Image::getOrientation(): Return value must be of type int, array returned in /var/www/html/lib/private/legacy/OC_Image.php:460
Stack trace:
#0 /var/www/html/lib/private/legacy/OC_Image.php(494): OC_Image->getOrientation()
#1 /var/www/html/lib/private/Preview/Image.php(52): OC_Image->fixOrientation()
#2 /var/www/html/lib/private/Preview/GeneratorHelper.php(64): OC\Preview\Image->getThumbnail(Object(OC\Files\Node\File), 800, 800)
#3 /var/www/html/lib/private/Preview/Generator.php(440): OC\Preview\GeneratorHelper->getThumbnail(Object(OC\Preview\JPEG), Object(OC\Files\Node\File), 800, 800)
#4 /var/www/html/lib/private/Preview/Generator.php(164): OC\Preview\Generator->getMaxPreview(Object(OC\Files\SimpleFS\SimpleFolder), Object(OC\Files\Node\File), 'image/jpeg', '')
#5 /var/www/html/lib/private/PreviewManager.php(212): OC\Preview\Generator->generatePreviews(Object(OC\Files\Node\File), Array, 'image/jpeg')
#6 /var/www/html/custom_apps/previewgenerator/lib/Command/Generate.php(230): OC\PreviewManager->generatePreviews(Object(OC\Files\Node\File), Array)
#7 /var/www/html/custom_apps/previewgenerator/lib/Command/Generate.php(212): OCA\PreviewGenerator\Command\Generate->parseFile(Object(OC\Files\Node\File))
#8 /var/www/html/custom_apps/previewgenerator/lib/Command/Generate.php(181): OCA\PreviewGenerator\Command\Generate->parseFolder(Object(OC\Files\Node\Folder), Array)
#9 /var/www/html/custom_apps/previewgenerator/lib/Command/Generate.php(129): OCA\PreviewGenerator\Command\Generate->generatePathPreviews(Object(OC\User\User), '/fmasotti/files...')
#10 /var/www/html/3rdparty/symfony/console/Command/Command.php(255): OCA\PreviewGenerator\Command\Generate->execute(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#11 /var/www/html/3rdparty/symfony/console/Application.php(1009): Symfony\Component\Console\Command\Command->run(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#12 /var/www/html/3rdparty/symfony/console/Application.php(273): Symfony\Component\Console\Application->doRunCommand(Object(OCA\PreviewGenerator\Command\Generate), Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#13 /var/www/html/3rdparty/symfony/console/Application.php(149): Symfony\Component\Console\Application->doRun(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#14 /var/www/html/lib/private/Console/Application.php(211): Symfony\Component\Console\Application->run(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#15 /var/www/html/console.php(100): OC\Console\Application->run()
#16 /var/www/html/occ(11): require_once('/var/www/html/c...')

As a temporary solution I modified the source code (/var/www/html/lib/private/legacy/OC_Image.php) like this:

public function getOrientation(): int {

    // rest of the function

    $this->exif = $exif;
+   if (gettype($exif['Orientation']) == 'array') {
+       return -1;
+   }
    return $exif['Orientation'];
}

By returning -1, when an array is detected, the program continues its job. I can't do many experiments since this is a production environment.

Start in lib/private/legacy/OC_Image.php at getOrientation(), then trace the call from lib/private/Preview/Image.php during preview generation. Investigate how an array-valued Orientation is handled and verify that regenerating previews no longer raises the reported TypeError.