Retry PNG to JPG conversion with debug enabled on failure

lib/upload_creator.rb

@@ -134,15 +134,13 @@ class UploadCreator
     jpeg_tempfile = Tempfile.new(["image", ".jpg"])
 
     OptimizedImage.ensure_safe_paths!(@file.path, jpeg_tempfile.path)
-    Discourse::Utils.execute_command(
-      'convert', @file.path,
-      '-auto-orient',
-      '-background', 'white',
-      '-interlace', 'none',
-      '-flatten',
-      '-quality', SiteSetting.png_to_jpg_quality.to_s,
-      jpeg_tempfile.path
-    )
+
+    begin
+      execute_convert(@file, jpeg_tempfile)
+    rescue
+      # retry with debugging enabled
+      execute_convert(@file, jpeg_tempfile, true)
+    end
 
     # keep the JPEG if it's at least 15% smaller
     if File.size(jpeg_tempfile.path) < filesize * 0.85
@@ -155,6 +153,19 @@ class UploadCreator
     end
   end
 
+  def execute_convert(input_file, output_file, debug = false)
+    command = ['convert', input_file.path,
+               '-auto-orient',
+               '-background', 'white',
+               '-interlace', 'none',
+               '-flatten',
+               '-quality', SiteSetting.png_to_jpg_quality.to_s]
+    command << '-debug' << 'all' if debug
+    command << output_file.path
+
+    Discourse::Utils.execute_command(*command, failure_message: "failed to convert png to jpg")
+  end
+
   def should_downsize?
     max_image_size > 0 && filesize >= max_image_size
   end