Observable<T>' is not assignable to type '<R>(operator: Operator<T, R>) => Observable<R>'

[ghost]

I am getting below error:

2-Final-Template (master)
$ npm install
npm WARN deprecated [email protected]: Typings is deprecated in favor of NPM @types -- see README for more information

> [email protected] postinstall F:\Angular_2.0_Learnings\Angular-2-Tutorials\Angular-2-Final-Template
> typings install

typings WARN deprecated 2016-9-14: "registry:dt/core-js#0.0.0+20160725163759" is deprecated (updated, replaced or removed)
typings WARN deprecated 2016-11-21: "registry:dt/node#6.0.0+20160909174046" is deprecated (updated, replaced or removed)
typings WARN deprecated 2016-10-25: "registry:dt/jasmine#2.2.0+20160621224255" is deprecated (updated, replaced or removed)

+-- core-js (global)
+-- jasmine (global)
`-- node (global)

npm notice created a lockfile as package-lock.json. You should commit this file.
npm WARN [email protected] No description
npm WARN [email protected] No repository field.
npm WARN optional SKIPPING OPTIONAL DEPENDENCY: [email protected] (node_modules\fsevents):
npm WARN notsup SKIPPING OPTIONAL DEPENDENCY: Unsupported platform for [email protected]: wanted {"os":"darwin","arch":"any"} (current: {"os":"win32","arch":"x64"})

added 408 packages from 288 contributors and audited 990 packages in 58.515s
found 4 vulnerabilities (2 low, 2 high)
  run `npm audit fix` to fix them, or `npm audit` for details

pc@DESKTOP-NQ639DU MINGW64 /f/Angular_2.0_Learnings/Angular-2-Tutorials/Angular-2-Final-Template (master)
$ npm start

> [email protected] start F:\Angular_2.0_Learnings\Angular-2-Tutorials\Angular-2-Final-Template
> tsc && concurrently "npm run tsc:w" "npm run lite"

node_modules/rxjs/Subject.d.ts(24,5): error TS2416: Property 'lift' in type 'Subject<T>' is not assignable to the same property in base type 'Observable<T>'.
  Type '<T, R>(operator: Operator<T, R>) => Observable<T>' is not assignable to type '<R>(operator: Operator<T, R>) => Observable<R>'.
    Type 'Observable<T>' is not assignable to type 'Observable<R>'.
      Type 'T' is not assignable to type 'R'.
node_modules/typescript/lib/lib.d.ts(105,14): error TS2300: Duplicate identifier 'PropertyKey'.
typings/globals/core-js/index.d.ts(3,14): error TS2300: Duplicate identifier 'PropertyKey'.
npm ERR! code ELIFECYCLE
npm ERR! errno 2
npm ERR! [email protected] start: `tsc && concurrently "npm run tsc:w" "npm run lite" `
npm ERR! Exit status 2
npm ERR!
npm ERR! Failed at the [email protected] start script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

npm ERR! A complete log of this run can be found in:
npm ERR!     C:\Users\pc\AppData\Roaming\npm-cache\_logs\2018-08-18T19_53_32_911Z-debug.log

pc@DESKTOP-NQ639DU MINGW64 /f/Angular_2.0_Learnings/Angular-2-Tutorials/Angular-2-Final-Template (master)
$ npm -v
6.4.0

pc@DESKTOP-NQ639DU MINGW64 /f/Angular_2.0_Learnings/Angular-2-Tutorials/Angular-2-Final-Template (master)
$ node -v
v8.11.3