Stop checking for non-existing conference_id in versions controller

app/controllers/admin/versions_controller.rb

@@ -7,11 +7,6 @@ module Admin
       @conf_ids_for_organizer = current_user.is_admin? ? Conference.pluck(:id) : Conference.with_role(:organizer, current_user).pluck(:id)
       @conference_id = params[:conference_id].to_i unless params[:conference_id].nil?
 
-      unless @conference_id.nil? || Conference.exists?(id: @conference_id)
-        redirect_to admin_revision_history_path, error: "Conference with ID #{@conference_id} does not exist!"
-        return
-      end
-
       return unless @conference_id.present?
       authorize! :index, PaperTrail::Version.new(conference_id: @conference_id)
       @versions = @versions.where(conference_id:  @conference_id)

spec/controllers/admin/versions_controller_spec.rb

@@ -99,12 +99,6 @@ describe Admin::VersionsController do
     end
 
     describe 'GET #index' do
-      it 'raises error if conference_id is invalid' do
-        sign_in admin
-        get :index, conference_id: 88
-        expect(flash[:error]).to match('Conference with ID 88 does not exist!')
-      end
-
       it 'raises error if user is not an organizer of specified conference' do
         user = create(:user)
         sign_in user