Command failed with exit code 1. (checkExecSyncError)

Here is the log I get when I try to run `yarn install`, `yarn add` or `node ./node_modules/postinstall-postinstall/run.js`:

I've tried to debug this and I've found out that spawnSync inside `checkExecSyncError` returns an error. This causes `checkExecSyncError` to return an error also. Workaround is replacing `execSync` with `exec`.
```
error ****/node_modules/postinstall-postinstall: Command failed.
Exit code: 1
Command: node ./run.js
Arguments:
Directory: ****/node_modules/postinstall-postinstall
Output:
error Command failed with exit code 1.
child_process.js:660
throw err;
^

Error: Command failed: yarn run postinstall
error Command failed with exit code 1.

at checkExecSyncError (child_process.js:621:11)
at execSync (child_process.js:657:15)
at Object. (****/node_modules/postinstall-postinstall/run.js:14:5)
```