Loading model on param route

I've successfully build out my app to have a proper child route and it works as it should when the user navigates through the site, but on load straight to the show route (exhibitions/slug) ember data seems to break; however, I'm still getting the proper response from the API. Here is my code, hope it makes sense..

routes/exhibitions

import Route from '@ember/routing/route';

const { set } = Ember;

export default Route.extend({
  model() {
    return this.store.findAll('exhibition');
  },
  setupController(controller, model) {
    set(controller, 'exhibitions', model);
  }
});

routes/exhibition

import Route from '@ember/routing/route';

const { set } = Ember;

export default Route.extend({
  model() {
    return this.store.findAll('exhibition');
  },
  setupController(controller, model) {
    set(controller, 'exhibitions', model);
  }
});

model for exhibition

import Contentful from 'ember-data-contentful/models/contentful';
import attr from 'ember-data/attr';
import { belongsTo, hasMany } from 'ember-data/relationships';

export default Contentful.extend({
  title: attr('string'),
  body: attr('string'),
  slug: attr('string')
});

router.js

import EmberRouter from '@ember/routing/router';
import config from './config/environment';

const Router = EmberRouter.extend({
  location: config.locationType,
  rootURL: config.rootURL
});

Router.map(function() {
  this.route('homepage', { path: '/' });
  this.route('exhibitions');
  this.route('exhibition', { path: 'exhibitions/:exhibition_slug'});
});

export default Router;

The error I'm getting in the console is:

Error while processing route: exhibition Cannot read property 'Entry' of undefined TypeError: Cannot read property 'Entry' of undefined

Let me know if anything else is needed!! Thank you!