support better errorhandling for codeharbor

app/services/exercise_service/push_external.rb

@@ -10,11 +10,7 @@ module ExerciseService
     def execute
       body = @zip.string
       begin
-        conn = Faraday.new(url: @codeharbor_link.push_url) do |faraday|
-          faraday.adapter Faraday.default_adapter
-        end
-
-        response = conn.post do |request|
+        response = connection.post do |request|
           request.headers['Content-Type'] = 'application/zip'
           request.headers['Content-Length'] = body.length.to_s
           request.headers['Authorization'] = 'Bearer ' + @codeharbor_link.api_key
@@ -26,5 +22,13 @@ module ExerciseService
         return e.message
       end
     end
+
+    private
+
+    def connection
+      Faraday.new(url: @codeharbor_link.push_url) do |faraday|
+        faraday.adapter Faraday.default_adapter
+      end
+    end
   end
 end