Error Cannot find module 'koa-passport' when npm start

[WahidinAlambiyah]

got error messages like this

[email protected] start E:\React Native Testing\ReactNativeSampleApp\server node --harmony server.js

module.js:557 throw err; ^

Error: Cannot find module 'koa-passport' at Function.Module._resolveFilename (module.js:555:15) at Function.Module._load (module.js:482:25) at Module.require (module.js:604:17) at require (internal/module.js:11:18) at Object. (E:\React Native Testing\ReactNativeSampleApp\server\server.js:4:18) at Module._compile (module.js:660:30) at Object.Module._extensions..js (module.js:671:10) at Module.load (module.js:573:32) at tryModuleLoad (module.js:513:12) at Function.Module._load (module.js:505:3) npm ERR! code ELIFECYCLE npm ERR! errno 1 npm ERR! [email protected] start: node --harmony server.js npm ERR! Exit status 1 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 WARN Local package.json exists, but node_modules missing, did you mean to install?