fix: Creating or Updating a story without attaching media (#979)

This fix checks for media existence before attempting to loop and attach
media.

Co-authored-by: Laura Mosher <lauramosher@users.noreply.github.com>

rails/app/controllers/dashboard/stories_controller.rb

@@ -24,7 +24,7 @@ def create
       @story = community_stories.new(story_params.except(:media))
 
       if @story.save
-        story_params[:media].each do |media|
+        story_params[:media]&.each do |media|
           m = @story.media.create(media: media)
         end
         redirect_to @story
@@ -45,7 +45,7 @@ def update
       @story = authorize community_stories.find(params[:id])
 
       if @story.update(story_params.except(:media))
-        story_params[:media].each do |media|
+        story_params[:media]&.each do |media|
           m = @story.media.create(media: media)
         end