I met an issue following the router config with the error below：

TypeError: Cannot create property 'type' on string 'content-api'
    at /Users/test/Documents/strapiDemo/node_modules/@strapi/strapi/lib/services/server/register-routes.js:71:21
    at /Users/test/Documents/strapiDemo/node_modules/lodash/lodash.js:4967:15

.....

and change to the below format that will be ok,

module.exports = {
  'content-api': {
     type: 'content-api',
    routes: [],
 }
}