Update tutorials_controller.rb

Author: lmrodriguezr

app/controllers/tutorials_controller.rb

@@ -49,7 +49,7 @@ def update
     elsif @tutorial.next_step(params.require(:tutorial), current_user)
       redirect_to(@tutorial.next_action, notice: @tutorial.notice)
     else
-      flash.now[:alert] = @tutorial.alert
+      flash.now[:alert] = @tutorial.alert if @tutorial.alert.present?
       render(:show)
     end