Fix Paperclip::Errors::NotIdentifiedByImageMagickError on invalid images

core/app/models/spree/image.rb

@@ -15,7 +15,7 @@ class Image < Asset
 
     # save the w,h of the original image (from which others can be calculated)
     # we need to look at the write-queue for images which have not been saved yet
-    after_post_process :find_dimensions
+    after_post_process :find_dimensions, if: :valid?
 
     # used by admin products autocomplete
     def mini_url

core/spec/models/spree/image_spec.rb

@@ -0,0 +1,23 @@
+require 'spec_helper'
+
+describe Spree::Image, type: :model do
+  context '#save' do
+    context 'invalid attachment' do
+      let(:invalid_image) { File.open(__FILE__) }
+      subject { described_class.new(attachment: invalid_image) }
+
+      it 'returns false' do
+        expect(subject.save).to be false
+      end
+    end
+
+    context 'valid attachment' do
+      let(:valid_image) { File.open(File.join('spec', 'fixtures', 'thinking-cat.jpg')) }
+      subject { described_class.new(attachment: valid_image) }
+
+      it 'returns true' do
+        expect(subject.save).to be true
+      end
+    end
+  end
+end