9:12

설명대로 다운로드받은 폴더에서 복사하고 새로 생성한 프로젝트에 붙여넣기했는데 저도 저 위와 같은 오류문구가 나오네요 ./src/app/services/item.service.ts:2:0-41 - Error: Module not found: Error: Can't resolve 'firebase/app' in 'C:\Users\jun\Documents\angular-08liter\angular-petlist\src\app\services' ./src/app/services/item.service.ts:3:0-27 - Error: Module not found: Error: Can't resolve 'firebase/database' in 'C:\Users\jun\Documents\angular-08liter\angular-petlist\src\app\services' Error: src/app/classes/item.ts:2:5 - error TS2564: Property 'key' has no initializer and is not definitely assigned in the constructor. 2 key: string; ~~~ Error: src/app/classes/item.ts:3:5 - error TS2564: Property 'id' has no initializer and is not definitely assigned in the constructor. 3 id: string; ~~ Error: src/app/classes/item.ts:4:5 - error TS2564: Property 'name' has no initializer and is not definitely assigned in the constructor. 4 name: string; ~~~~ Error: src/app/classes/item.ts:5:5 - error TS2564: Property 'available' has no initializer and is not definitely assigned in the constructor. 5 available: boolean; ~~~~~~~~~ Error: src/app/item/item.component.html:4:27 - error TS2341: Property 'item' is private and only accessible within class 'ItemComponent'. 4 ~~~~ src/app/item/item.component.ts:8:16 8 templateUrl: './item.component.html', m ~~~~~~~~~~~~~~~~~~~~~~~ Error occurs in the template of component ItemComponent. Error: src/app/item/item.component.html:4:27 - error TS2341: Property 'item' is private and only accessible within class 'ItemComponent'. 4 ~~~~ src/app/item/item.component.ts:8:16 8 templateUrl: './item.component.html', ~~~~~~~~~~~~~~~~~~~~~~~ Error occurs in the template of component ItemComponent. Error: src/app/item/item.component.html:9:27 - error TS2341: Property 'item' is private and only accessible within class 'ItemComponent'. 9 ~~~~ src/app/item/item.component.ts:8:16 8 templateUrl: './item.component.html', ~~~~~~~~~~~~~~~~~~~~~~~ Error occurs in the template of component ItemComponent. Error: src/app/item/item.component.html:9:27 - error TS2341: Property 'item' is private and only accessible within class 'ItemComponent'. 9 ~~~~ src/app/item/item.component.ts:8:16 8 templateUrl: './item.component.html', ~~~~~~~~~~~~~~~~~~~~~~~ Error occurs in the template of component ItemComponent. Error: src/app/item/item.component.html:14:27 - error TS2341: Property 'item' is private and only accessible within class 'ItemComponent'. 14 ~~~~ src/app/item/item.component.ts:8:16 8 templateUrl: './item.component.html', ~~~~~~~~~~~~~~~~~~~~~~~ Error occurs in the template of component ItemComponent. Error: src/app/item/item.component.html:14:27 - error TS2341: Property 'item' is private and only accessible within class 'ItemComponent'. 14 ~~~~ src/app/item/item.component.ts:8:16 8 templateUrl: './item.component.html', ~~~~~~~~~~~~~~~~~~~~~~~ Error occurs in the template of component ItemComponent. Error: src/app/item/item.component.ts:34:9 - error TS2322: Type 'Item | undefined' is not assignable to type 'Item'. Type 'undefined' is not assignable to type 'Item'. 34 this.item = this.itemService.getItem(id); ~~~~~~~~~ Error: src/app/services/item.service.ts:4:27 - error TS2307: Cannot find module 'firebase/app' or its corresponding type declarations. 4 import * as firebase from 'firebase/app'; ~~~~~~~~~~~~~~ Error: src/app/services/item.service.ts:36:33 - error TS7006: Parameter 'snapshot' implicitly has an 'any' type. 36 this.itemList.on('value', snapshot => { ~~~~~~~~ Error: src/app/services/item.service.ts:37:27 - error TS7006: Parameter 'snap' implicitly has an 'any' type. 37 snapshot.forEach( snap => {