Unexpected token when importing from dependency written in TypeScript

Bug report

Describe the bug

I have just started transitioning an existing webapp to Next.js. Our current setup is bundled and deployed via rollup. We have a dependency which is an API client written in TypeScript, which is not transpiled until our app is bundled. I was under the impression that Next.js would handle this automatically, but it seems to be running into a problem. When I load my app, I get this error:

./node_modules/@kalos-core/kalos-rpc/Event/index.ts 12:20
Module parse failed: Unexpected token (12:20)
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
| 
| class EventClient extends BaseClient {
>   constructor(userID: number, host?: string) {
|     super(userID, host);
|   }

I’m guessing I need to add a custom webpack config with ts-loader? But I’m a bit confused since my components are also written in TypeScript and they don’t throw errors.

Expected behavior

Next.js to transpile my dependencies

System information

• OS: [macOS]
• Browser (if applies) [chrome]
• Version of Next.js: [9.2.1]

[jamesmosier]

Next does not transpile any third party node modules. Also any typescript files outside of the your main application source directory will not be transpiled either (see #9474 for more info on this one) .

[balazsorban44]

This issue has been automatically locked due to no recent activity. If you are running into a similar issue, please create a new issue with the steps to reproduce. Thank you.