Why I;m getting error when implementing my database

here is the adapter In Ember Data, an Adapter determines how data is persisted to a backend data store. Things such as the backend host, URL format and headers used to talk to a REST API can all be configured in an adapter.

/* adapters/application.js */

import FirebaseAdapter from "emberfire/adapters/firebase";
export default FirebaseAdapter.extend({});

A Controller is routable object which receives a single property from the Route .. here is the controller

/* controllers/cars.js */

import Controller from "@ember/controller";
export default Controller.extend({
  actions: {
deleteCar(id) {
  this.get("store")
    .findRecord("car", id, { reload: true })
    .then(car => {
      car.destroyRecord();
      car.save();
      //self.transitionToRoute("cars");
    });
   }
   }
  });

/* controllers/cars/edit.js */

import Controller from "@ember/controller";
export default Controller.extend({
actions: {
  editCar: function(id) {
  var self = this;

  var make = this.get("model.make");
  var model = this.get("model.model");
  var year = this.get("model.year");

  this.store.findRecord("car", id).then(function(car) {
    car.set("make", make);
    car.set("model", model);
    car.set("year", year);
    car.save();
    self.transitionToRoute("cars");
    });
    }
    }
    });

   /* controllers/cars/new.js */

   import Controller from "@ember/controller";
   export default Controller.extend({
   actions: {
     addCar: function() {
      var self = this;
      var rand = Math.floor(Math.random() * 10000 + 1);
      var newCar = this.store.createRecord("car", {
    id: rand,
    make: this.get("carMake"),
    model: this.get("carModel"),
    year: this.get("carYear")
    });
    newCar.save();
    self.transitionToRoute("cars");
   }
   }
   });

In Ember Data, models are objects that represent the underlying data that your application presents to the user. Note that Ember Data models are a different concept than the model method on Routes, although they share the same name .. here is the model

   /* models/cars.js */

   import DS from "ember-data";
   export default DS.Model.extend({
      make: DS.attr("string"),
      model: DS.attr("string"),
      year: DS.attr("string")
    });

In Ember, when we want to make a new page that can be visited using a URL, we need to generate a "route" using Ember CLI .. here is the routes

  /* routes/cars.js */

  import Route from "@ember/routing/route";
  export default Route.extend({
   model() {
      return this.store.findAll("car", {
      orderBy: "make"
     });
    }
   });

 /* routes/cars/edit.js */

 import Route from '@ember/routing/route';
   export default Route.extend({
   });

 /* routes/cars/new.js */

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

  export default Route.extend({
   model() {
       return this.store.findAll("car");
    }
    });

The EmberRouter class manages the application state and URLs .. here is the router

  /* 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("cars", function() {
      this.route("new");
      this.route("edit", { path: "/edit/:car_id" });
    });
    this.route("users");
   });
   export default Router;