Merge pull request #4 from facebook/next

Ensure workspaces key exists in parent package.json (facebook#3989)

Author: tvalentius

packages/react-scripts/config/paths.js

@@ -140,6 +140,9 @@ const getMonorepoPkgPaths = () => {
   if (monoPkgPath) {
     // get monorepo config from yarn workspace
     const pkgPatterns = require(monoPkgPath).workspaces;
+    if (pkgPatterns == null) {
+      return [];
+    }
     const pkgPaths = findPkgs(path.dirname(monoPkgPath), pkgPatterns);
     // only include monorepo pkgs if app itself is included in monorepo
     if (pkgPaths.indexOf(appDirectory) !== -1) {