ng serve error: You seem to not be depending on "@angular/core"

I keep getting the error You seem to not be depending on "@angular/core" I have tried everything on the stackoverflow it says from using npm install, npm link to everything. Does anyone know how to solve the error?

try installing @angular/core but gets this error

C:\xampp\htdocs\kindyportalBackend>npm install @angular/core
npm ERR! code ERESOLVE
npm ERR! ERESOLVE could not resolve
npm ERR!
npm ERR! While resolving: @angular-devkit/[email protected]
npm ERR! Found: [email protected]
npm ERR! node_modules/jest
npm ERR!   peer jest@">=26 <27" from [email protected]
npm ERR!   node_modules/ts-jest
npm ERR!     dev ts-jest@"^26.5.2" from the root project
npm ERR!   dev jest@"^26.6.3" from the root project
npm ERR!
npm ERR! Could not resolve dependency:
npm ERR! peerOptional jest@"^29.5.0" from @angular-devkit/[email protected]
npm ERR! node_modules/@angular-devkit/build-angular
npm ERR!   dev @angular-devkit/build-angular@"^16.2.0" from the root project
npm ERR!
npm ERR! Conflicting peer dependency: [email protected]
npm ERR! node_modules/jest
npm ERR!   peerOptional jest@"^29.5.0" from @angular-devkit/[email protected]
npm ERR!   node_modules/@angular-devkit/build-angular
npm ERR!     dev @angular-devkit/build-angular@"^16.2.0" from the root project
npm ERR!
npm ERR! Fix the upstream dependency conflict, or retry
npm ERR! this command with --force or --legacy-peer-deps
npm ERR! to accept an incorrect (and potentially broken) dependency resolution.
npm ERR!
npm ERR!
npm ERR! For a full report see:
npm ERR! C:\Users\hemlata.mahaur\AppData\Local\npm-cache\_logs\2023-08-30T23_17_40_449Z-eresolve-report.txt

npm ERR! A complete log of this run can be found in: C:\Users\hemlata.mahaur\AppData\Local\npm-cache\_logs\2023-08-30T23_17_40_449Z-debug-0.log

After using --force it works and I can install @angular/core. Now if I run ng serve I get this error

An unhandled exception occurred: error TS500: Error: ENOENT: no such file or directory, lstat 'C:/xampp/htdocs/kindyportalBackend/src/tsconfig.app.json'
    at Object.lstatSync (node:fs:1668:3)
    at NodeJSFileSystem.lstat (file:///C:/xampp/htdocs/kindyportalBackend/node_modules/@angular/compiler-cli/bundles/chunk-TBUSSXUA.js:341:16)
    at calcProjectFileAndBasePath (file:///C:/xampp/htdocs/kindyportalBackend/node_modules/@angular/compiler-cli/bundles/chunk-6SPHWESC.js:7650:29)
    at readConfiguration (file:///C:/xampp/htdocs/kindyportalBackend/node_modules/@angular/compiler-cli/bundles/chunk-6SPHWESC.js:7676:39)
    at readTsconfig (C:\xampp\htdocs\kindyportalBackend\node_modules\@angular-devkit\build-angular\src\utils\read-tsconfig.js:49:26)
    at async configureI18nBuild (C:\xampp\htdocs\kindyportalBackend\node_modules\@angular-devkit\build-angular\src\utils\i18n-options.js:125:22)
    at async generateI18nBrowserWebpackConfigFromContext (C:\xampp\htdocs\kindyportalBackend\node_modules\@angular-devkit\build-angular\src\utils\webpack-browser-config.js:66:36)
    at async setup (C:\xampp\htdocs\kindyportalBackend\node_modules\@angular-devkit\build-angular\src\builders\dev-server\webpack-server.js:96:34)

See "C:\Users\HEMLAT~1.MAH\AppData\Local\Temp\ng-1nlzeP\angular-errors.log" for further details.

what file is that and how can I install it? I copy pasted this file

Is it the right file?

I am running this in backend project folder or do I need to run ng serve in front end project?

After adding that file I ran ng serve and gets this error

BREAKING CHANGE: webpack < 5 used to include polyfills for node.js core modules by default.
This is no longer the case. Verify if you need this module and configure a polyfill for it.

If you want to include a polyfill, you need to:
        - add a fallback 'resolve.fallback: { "url": require.resolve("url/") }'
        - install 'url'
If you don't want to include a polyfill, you can use an empty module like this:
        resolve.fallback: { "url": false }

./node_modules/nodemailer/lib/fetch/index.js:6:13-28 - Error: Module not found: Error: Can't resolve 'zlib' in 'C:\xampp\htdocs\kindyportalBackend\node_modules\nodemailer\lib\fetch'

BREAKING CHANGE: webpack < 5 used to include polyfills for node.js core modules by default.
This is no longer the case. Verify if you need this module and configure a polyfill for it.

If you want to include a polyfill, you need to:
        - add a fallback 'resolve.fallback: { "zlib": require.resolve("browserify-zlib") }'
        - install 'browserify-zlib'
If you don't want to include a polyfill, you can use an empty module like this:
        resolve.fallback: { "zlib": false }