[fix] live_events return json; use the provided happening_now? function

app/controllers/conferences_controller.rb

@@ -114,7 +114,7 @@ class ConferencesController < ApplicationController
 
   def live_events
     conference = Conference.find_by(short_title: params[:conference_id])
-    conference.find_live_events.to_json
+    render json: conference.find_live_events.to_json
   end
 
   private

app/models/conference.rb

@@ -785,13 +785,7 @@ class Conference < ApplicationRecord
   end
 
   def find_live_events
-    live_events = []
-    program.events.each do |event|
-      if event.live?
-        live_events.append(event)
-      end
-    end
-    live_events
+    program.events.select(&:happening_now?)
   end
 
   private

app/models/event.rb

@@ -337,10 +337,6 @@ class Event < ApplicationRecord
     time <=> other.time
   end
 
-  def is_live?
-    time >= Time.now && Time.now <= time + event_type.length
-  end
-
   private
 
   ##