Fixed a bug where errors in processing would create further errors in attachment…

Fixed a bug where errors in processing would create further errors in attachment saving. Will also raise if there are no processors defined for a style.

lib/paperclip/attachment.rb

@@ -326,11 +326,13 @@ module Paperclip
       log("Post-processing #{name}")
       @styles.each do |name, args|
         begin
-          @queued_for_write[name] = @queued_for_write[:original]
-          args[:processors].each do |processor|
-            @queued_for_write[name] = Paperclip.processor(processor).make(@queued_for_write[name], args)
+          raise RuntimeError.new("Style #{name} has no processors defined.") if args[:processors].blank?
+          @queued_for_write[name] = args[:processors].inject(@queued_for_write[:original]) do |file, processor|
+            log("Processing #{name} #{file} in the #{processor} processor.")
+            Paperclip.processor(processor).make(file, args)
           end
         rescue PaperclipError => e
+          log("An error was received while processing: #{e.inspect}")
           (@errors[:processing] ||= []) << e.message if @whiny
         end
       end

test/attachment_test.rb

@@ -210,6 +210,17 @@ class AttachmentTest < Test::Unit::TestCase
     end
   end
 
+  context "An attachment with no processors defined" do
+    setup do
+      rebuild_model :processors => [], :styles => {:something => 1}
+      @dummy = Dummy.new
+      @file = StringIO.new("...")
+    end
+    should "raise when assigned to" do
+      assert_raises(RuntimeError){ @dummy.avatar = @file }
+    end
+  end
+
   context "Assigning an attachment with post_process hooks" do
     setup do
       rebuild_model :styles => { :something => "100x100#" }