Added more error checking in rcube_image::resize()

program/lib/Roundcube/rcube_image.php

@@ -93,6 +93,10 @@ class rcube_image
         $convert = $rcube->config->get('im_convert_path', false);
         $props   = $this->props();
 
+        if (empty($props)) {
+            return false;
+        }
+
         if (!$filename) {
             $filename = $this->image_file;
         }
@@ -148,6 +152,10 @@ class rcube_image
                 return false;
             }
 
+            if ($image === false) {
+                return false;
+            }
+
             $scale = $size / max($props['width'], $props['height']);
 
             // Imagemagick resize is implemented in shrinking mode (see -resize argument above)