Allow/Fix precompiled assets with Propshaft pipeline

lib/wicked_pdf/wicked_pdf_helper/assets.rb

@@ -28,17 +28,9 @@ def initialize(url, response)
         end
       end
 
-      class PropshaftAsset < SimpleDelegator
-        def content_type
-          super.to_s
-        end
-
+      class PropshaftAsset < LocalAsset
         def to_s
-          content
-        end
-
-        def filename
-          path.to_s
+          Rails.application.assets.resolver.read(path)
         end
       end
 
@@ -200,7 +192,7 @@ def find_asset(path)
         if Rails.application.assets.respond_to?(:find_asset)
           Rails.application.assets.find_asset(path, :base_path => Rails.application.root.to_s)
         elsif defined?(Propshaft::Assembly) && Rails.application.assets.is_a?(Propshaft::Assembly)
-          PropshaftAsset.new(Rails.application.assets.load_path.find(path))
+          PropshaftAsset.new(path)
         elsif Rails.application.respond_to?(:assets_manifest)
           asset_path = File.join(Rails.application.assets_manifest.dir, Rails.application.assets_manifest.assets[path])
           LocalAsset.new(asset_path) if File.file?(asset_path)