Problema ao rodar o projeto api back

Estou com um problema para rodar a api back referente ao curso "Angular parte 1: produtividade e organização com framework SPA". Apos o npm start ocorre o seguinte erro:

$ npm start

> alurapic@1.0.0 start
> node server.js      

node:internal/modules/cjs/loader:936
  throw err;
  ^

Error: Cannot find module 'express'
Require stack:
- C:\Users\rapha\alura\api\config\express.js
- C:\Users\rapha\alura\api\server.js
    at Function.Module._resolveFilename (node:internal/modules/cjs/loader:933:15)
    at Function.Module._load (node:internal/modules/cjs/loader:778:27)
    at Module.require (node:internal/modules/cjs/loader:1005:19)
    at require (node:internal/modules/cjs/helpers:102:18)
    at Object.<anonymous> (C:\Users\rapha\alura\api\config\express.js:1:17)      
    at Module._compile (node:internal/modules/cjs/loader:1105:14)
    at Object.Module._extensions..js (node:internal/modules/cjs/loader:1159:10)  
    at Module.load (node:internal/modules/cjs/loader:981:32)
    at Function.Module._load (node:internal/modules/cjs/loader:822:12)
    at Module.require (node:internal/modules/cjs/loader:1005:19) {
  code: 'MODULE_NOT_FOUND',
  requireStack: [
    'C:\\Users\\rapha\\alura\\api\\config\\express.js',
    'C:\\Users\\rapha\\alura\\api\\server.js'
  ]
}