Error with Web Interface and Trivia

TypeError: C:\Users\Administrator\Desktop\AB 4\GAwesomeBot-development\Web\views\pages\admin-ongoing-activities.ejs:66
   64| <div class="card-content">
   65| <h3 class="title is-3 has-text-centered">
>> 66| <%= trivia[i].set.charAt(0) + trivia[i].set.slice(1) %>
   67| </h3>
   68| <div class="level is-mobile">
   69| <div class="level-item has-text-centered">

trivia[i].set.charAt is not a function
   at eval (eval at compile (C:\Users\Administrator\Desktop\AB 4\GAwesomeBot-development\node_modules\ejs\lib\ejs.js:481:12), <anonymous>:526:38)
   at returnedFn (C:\Users\Administrator\Desktop\AB 4\GAwesomeBot-development\node_modules\ejs\lib\ejs.js:512:17)
   at View.exports.renderFile [as engine] (C:\Users\Administrator\Desktop\AB 4\GAwesomeBot-development\node_modules\ejs\lib\ejs.js:364:31)
   at View.render (C:\Users\Administrator\Desktop\AB 4\GAwesomeBot-development\node_modules\express\lib\view.js:126:8)
   at tryRender (C:\Users\Administrator\Desktop\AB 4\GAwesomeBot-development\node_modules\express\lib\application.js:639:10)
   at EventEmitter.render (C:\Users\Administrator\Desktop\AB 4\GAwesomeBot-development\node_modules\express\lib\application.js:591:3)
   at ServerResponse.render (C:\Users\Administrator\Desktop\AB 4\GAwesomeBot-development\node_modules\express\lib\response.js:960:7)
   at checkAuth (C:\Users\Administrator\Desktop\AB 4\GAwesomeBot-development\Web\WebServer.js:3289:8)
   at db.servers.findOne (C:\Users\Administrator\Desktop\AB 4\GAwesomeBot-development\Web\WebServer.js:710:10)
   at Query.<anonymous> (C:\Users\Administrator\Desktop\AB 4\GAwesomeBot-development\node_modules\mongoose\lib\model.js:3419:16)
   at C:\Users\Administrator\Desktop\AB 4\GAwesomeBot-development\node_modules\kareem\index.js:264:21
   at C:\Users\Administrator\Desktop\AB 4\GAwesomeBot-development\node_modules\kareem\index.js:127:16
   at _combinedTickCallback (internal/process/next_tick.js:67:7)
   at process._tickDomainCallback [as _tickCallback] (internal/process/next_tick.js:122:9)