Fix regression in resizing JPEG images with Imagick (#5376)

CHANGELOG

@@ -25,6 +25,7 @@ CHANGELOG Roundcube Webmail
 - Managesieve: Unhide advanced rule controls if there are inputs with errors
 - Managesieve: Display warning message when filter form contains errors
 - Enigma: Add possibility to configure gpg-agent binary location (enigma_pgp_agent)
+- Fix regression in resizing JPEG images with Imagick (#5376)
 
 RELEASE 1.2.1
 -------------

program/lib/Roundcube/rcube_image.php

@@ -167,9 +167,15 @@ class rcube_image
                         try {
                             $image = new Imagick($this->image_file);
 
+                            try {
+                                // it throws exception on formats not supporting these features
                                 $image->setImageBackgroundColor('white');
                                 $image->setImageAlphaChannel(11);
                                 $image->mergeImageLayers(Imagick::LAYERMETHOD_FLATTEN);
+                            }
+                            catch (Exception $e) {
+                                // ignore errors
+                            }
 
                             $image->setImageColorspace(Imagick::COLORSPACE_SRGB);
                             $image->setImageCompressionQuality(75);