ng serve issue: Error: ./node_modules/exceljs/dist/es5/exceljs.browser.js #259

I receive the following errors when I try to install

*******~/attack-navigator/nav-app$ sudo ng serve
✔ Browser application bundle generation complete.

Initial Chunk Files | Names | Size
vendor.js | vendor | 7.09 MB
scripts.js | scripts | 2.70 MB
main.js | main | 1.09 MB
polyfills.js | polyfills | 385.51 kB
styles.css | styles | 75.98 kB
runtime.js | runtime | 6.15 kB

                | Initial Total |  11.33 MB

Build at: 2021-01-15T20:17:05.633Z - Hash: 2a0c1d7434cfd49d0f92 - Time: 17766ms

Warning: Zone.js does not support native async/await in ES2017+.
These blocks are not intercepted by zone.js and will not triggering change detection.
See: angular/zone.js#1140 for more information.

Warning: /home/debianadmin/attack-navigator/nav-app/src/app/app.module.ts depends on 'rxjs/add/operator/map'. CommonJS or AMD dependencies can cause optimization bailouts.
For more info see: https://angular.io/guide/build#configuring-commonjs-dependencies

Error: ./node_modules/exceljs/dist/es5/exceljs.browser.js
Module not found: Error: Can't resolve 'core-js/modules/es.array.find' in '/home/debianadmin/attack-navigator/nav-app/node_modules/exceljs/dist/es5'

Error: ./node_modules/exceljs/dist/es5/exceljs.browser.js
Module not found: Error: Can't resolve 'core-js/modules/es.array.find-index' in '/home/debianadmin/attack-navigator/nav-app/node_modules/exceljs/dist/es5'

Error: ./node_modules/exceljs/dist/es5/exceljs.browser.js
Module not found: Error: Can't resolve 'core-js/modules/es.array.includes' in '/home/debianadmin/attack-navigator/nav-app/node_modules/exceljs/dist/es5'

Error: ./node_modules/exceljs/dist/es5/exceljs.browser.js
Module not found: Error: Can't resolve 'core-js/modules/es.array.iterator' in '/home/debianadmin/attack-navigator/nav-app/node_modules/exceljs/dist/es5'

Error: ./node_modules/exceljs/dist/es5/exceljs.browser.js
Module not found: Error: Can't resolve 'core-js/modules/es.number.is-nan' in '/home/debianadmin/attack-navigator/nav-app/node_modules/exceljs/dist/es5'

Error: ./node_modules/exceljs/dist/es5/exceljs.browser.js
Module not found: Error: Can't resolve 'core-js/modules/es.object.assign' in '/home/debianadmin/attack-navigator/nav-app/node_modules/exceljs/dist/es5'

Error: ./node_modules/exceljs/dist/es5/exceljs.browser.js
Module not found: Error: Can't resolve 'core-js/modules/es.object.keys' in '/home/debianadmin/attack-navigator/nav-app/node_modules/exceljs/dist/es5'

Error: ./node_modules/exceljs/dist/es5/exceljs.browser.js
Module not found: Error: Can't resolve 'core-js/modules/es.object.values' in '/home/debianadmin/attack-navigator/nav-app/node_modules/exceljs/dist/es5'

Error: ./node_modules/exceljs/dist/es5/exceljs.browser.js
Module not found: Error: Can't resolve 'core-js/modules/es.promise' in '/home/debianadmin/attack-navigator/nav-app/node_modules/exceljs/dist/es5'

Error: ./node_modules/exceljs/dist/es5/exceljs.browser.js
Module not found: Error: Can't resolve 'core-js/modules/es.string.from-code-point' in '/home/debianadmin/attack-navigator/nav-app/node_modules/exceljs/dist/es5'

Error: ./node_modules/exceljs/dist/es5/exceljs.browser.js
Module not found: Error: Can't resolve 'core-js/modules/es.string.includes' in '/home/debianadmin/attack-navigator/nav-app/node_modules/exceljs/dist/es5'

Error: ./node_modules/exceljs/dist/es5/exceljs.browser.js
Module not found: Error: Can't resolve 'core-js/modules/es.symbol' in '/home/debianadmin/attack-navigator/nav-app/node_modules/exceljs/dist/es5'

Error: ./node_modules/exceljs/dist/es5/exceljs.browser.js
Module not found: Error: Can't resolve 'core-js/modules/es.symbol.async-iterator' trie'/home/debianadmin/attack-navigator/nav-app/node_modules/exceljs/dist/es5'

** Angular Live Development Server is listening on localhost:4200, open your browser on http://localhost:4200/ **

I opened browser on http://localhost:4200/ and only get" Cannot GET / "
tried "npm run postinstall" and still having the same issue.