Merge branch 'issue/354' into 'master'

fixed return 404 instead of 500 when object doesn't exist

See merge request portalmec/portalmec!501

.gitlab-ci.yml

+image: ruby:2.3.1
+
 services:
   - postgres:9.5
   - elasticsearch:2

app/controllers/concerns/sociable_controller.rb

@@ -57,7 +57,7 @@ module SociableController
 
   def view_object!
     # Change request.remote_ip to req.env["HTTP_X_REAL_IP"] in production
-    sociable.view(current_user, request.remote_ip)
+    sociable.view(current_user, request.remote_ip) unless sociable.nil?
   end
 
 end

app/controllers/v1/learning_objects_controller.rb

@@ -132,10 +132,14 @@ class V1::LearningObjectsController < ApplicationController
   def set_learning_object
     #check if user is admin to show destroyed object
     if current_user.try(:is_admin?)
-      @learning_object ||= LearningObject.unscoped.find(params[:id])
+      @learning_object ||= LearningObject.unscoped.find_by_id(params[:id])
     else
-      @learning_object ||= LearningObject.find(params[:id])
+      @learning_object ||= LearningObject.find_by_id(params[:id])
     end
+    if @learning_object.nil?
+      render status: :not_found
+    end
+    @learning_object
   end
 
   def set_new_learning_object