importHelpers option is broken and fails with "Cannot find module 'tslib'"

[lhecker]

The new importHelpers feature in TypeScript does not seem to work with awesome-typescript-loader.

Setting this option in the tsconfig.json file:

{
    "compilerOptions": {
        "importHelpers": true
    }
}

causes the following error:

ERROR in [default]
Cannot find module 'tslib'.

even though the tslib module was successfully included by WebPack:

  [234] ./~/tslib/tslib.js 4.26 kB {0} [built]

Anything I can do to help you fix this issue? 🙂

[Jessidhia]

This error seems is actually emitted by tsc itself.

When I checked, tsc was actually using classic module resolution due to having "module": "es2015" in the settings, which, of course, prevented it from finding the tslib inside node_modules. Adding "moduleResolution": "node" fixed it.

[Delagen]

@Kovensky can it be resolved using paths section of tsconfig.json?

[timocov]

@Kovensky With "target": "es5" it happens too (for es5 node module resolution is used by default).

Also, if you run ./node_modules/.bin/tsc --noEmit then no error happens (in my case of course)
ts-loader does not output that error.

[timocov]

Also, result bundle have tslib module (and all requires is fine) but error happened

[timocov]

Seems that in 3.0.0-beta.5 it is fixed.

I had to set moduleResolution to node in my tsconfig.json to get the error to go away.

[Delagen]

if tslib is not direct dependency and resolved via webpack this message emits