How to fix "You may need an appropriate loader to handle this file type, currently no loaders are configured to process this file."

Question

I use next.js. When exporting a type in a file index.ts in a third party package an error occurs.

Module parse failed: Unexpected token (23:7)
    You may need an appropriate loader to handle this file type, currently no loaders are configured to process this file. See https://webpack.js.org/concepts#loaders
    > export type { Validate } from './src/nullable'

Answer 1

in package.json, assuming the following dependency is added

"@yourproject/your-project": "file:../your-project",

then in next.config, add transpilePackages: ['@yourproject/your-project'],.  This allows the loader to work directly on .ts files.

transpilePackages: ['@yourproject/your-project'],
webpack: (config) => {
       config.resolve.extensionAlias = {
      ".js": [".ts", ".tsx", ".js", ".jsx"],
      ".mjs": [".mts", ".mjs"],
      ".cjs": [".cts", ".cjs"],
    };
    return config;
  },