Cannot build next.js project if expo-router is in node_modules

[tamagokun]

Summary

I believe this may be the same issue as this comment: #323 (comment)

Running next build will cause next.js to do type checking on the project. Even though tsconfig is setup properly (proper include, exclude: ["node_modules"], skipLibCheck: true), TS will still start type checking expo-router and throw an error:

../../node_modules/expo-router/src/fork/getStateFromPath.ts:475:3
Type error: Unused '@ts-expect-error' directive.

  473 |   parentScreens.push(screen);
  474 |
> 475 |   // @ts-expect-error
      |   ^
  476 |   const config = routeConfig[screen];
  477 |
  478 |   if (typeof config === "string") {

To be clear, i'm not using expo-router on web, or in next.js. It's part of a shared component that gets used in a native expo project and a next.js web project.

Minimal reproducible example

1. Clone this minimal project: https://github.com/tamagokun/nextjs-expo-router-issue
2. Run yarn build
3. See ts error from expo-router

[mauricedoepke]

Looks like it was just forgotten to get rid of the // @ts-expect-error comment. Maybe you can locally try out if deleting it fixes your issue and the open a pr for that.

[tamagokun]

Trying to appease typescript by changing things inside of expo-router does not work, as it just runs into the next error.

For example, there was a different error that I ran into before the one I posted above, which I tried to fix locally, and it just led to the next one:

../../node_modules/expo-router/src/exports.ts:19:10
Type error: Re-exporting a type when the '--isolatedModules' flag is provided requires using 'export type'.

  17 | export { ExpoRoot } from "./ExpoRoot";
  18 | export { Unmatched } from "./views/Unmatched";
> 19 | export { ErrorBoundaryProps } from "./views/Try";
     |          ^
  20 | export { ErrorBoundary } from "./views/ErrorBoundary";

The issue here is that next.js should not be checking types of expo-router in node_modules. This seems to be related to a weird limitation with typescript and how expo-router provides their "types" setting in package.json

The comment I linked to above also links to a typescript issue that further illustrates the problem: #323 (comment)

[tamagokun]

Looks like this PR fixes the issue: #372

[tamagokun]

i've confirmed this is fixed in 1.3.0 🎉