fixes #3382

app/controllers/sources_controller.rb

@@ -1,5 +1,6 @@
 class SourcesController < ApplicationController
   respond_to :json, :xml
+  rescue_from Sources::Site::NoStrategyError, :with => :no_strategy
 
   def show
     @source = Sources::Site.new(params[:url], :referer_url => params[:ref])
@@ -9,4 +10,10 @@ class SourcesController < ApplicationController
       format.xml { render xml: @source.to_h.to_xml(root: "source") }
     end
   end
+
+protected
+
+  def no_strategy
+    render json: {message: "Unsupported site"}.to_json, status: 400
+  end
 end

app/logical/image_proxy.rb

@@ -1,6 +1,8 @@
 class ImageProxy
   def self.needs_proxy?(url)
     fake_referer_for(url).present?
+  rescue Sources::Site::NoStrategyError
+    false
   end
 
   def self.fake_referer_for(url)

app/logical/sources/site.rb

@@ -2,6 +2,8 @@
 
 module Sources
   class Site
+    class NoStrategyError < RuntimeError ; end
+
     attr_reader :url, :strategy
     delegate :get, :get_size, :site_name, :artist_name,
       :profile_url, :image_url, :tags, :artists, :unique_id,
@@ -22,6 +24,8 @@ module Sources
           @strategy = strategy.new(url, referer_url)
           break
         end
+
+        raise NoStrategyError.new
       end
     end