Erro na transformação do es6 para es5

SyntaxError: js/app-es6/service/HTTPservice.js: Unexpected token (16:28)
  14 |   post(url, dado){
  15 |           return fetch(url, {
> 16 |                   headers:{'Content-type' , 'application/json'}
     |                                           ^
  17 |           })
  18 |   }
  19 |
npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! client@1.0.0 build: `babel js/app-es6 -d js/app `
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the client@1.0.0 build 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\User\AppData\Roaming\npm-cache\_logs\2019-11-17T21_35_00_328Z-debug.log

No terminal esta aparecendo que não esta aceitando a virgula e não sei como proceder