cannot read property 'baseUrl' of undefined error while starting nodeJs server

I'm working on a reactJs application. I'm doing all the development by starting a nodeJs server. When I try running command npm run start, the nodeJs server fails to start with below mentioned error:

TypeError: Cannot read property 'baseUrl' of undefined at getWebpackConfig (C:\Source\sam\ui\jsx.v2\devServer.js:145:44) at Object. (C:\Source\sam\ui\jsx.v2\devServer.js:13:23) at Module._compile (module.js:570:32) at Object.Module._extensions..js (module.js:579:10) at Module.load (module.js:487:32) at tryModuleLoad (module.js:446:12) at Function.Module._load (module.js:438:3) at Module.runMain (module.js:604:10) at run (bootstrap_node.js:393:7) at startup (bootstrap_node.js:150:9)

My devServerConfig.json file looks like below:

{
    "baseUrl": "http://localhost:8080/",
    "basicAuth":"myCurrentDomain\\somefirstName.someLastName:*****",
    "useHTTPS": false,
    "certificateRelativePath": "if using HTTPS provide relative path to .pfx certificate file",
    "certificatePassword": "myCertificatePassword"
    "users":[{
    "username":"somefirstName.someLastName",
    "password":"*****",
    "domain":"myCurrentDomain"
    }]
}

via RBT