module: fix check exports issue in cjs module loading

Refs: https://github.com/nodejs/node/pull/31001#issuecomment-576353389

PR-URL: https://github.com/nodejs/node/pull/31427
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Shelley Vohr <codebytere@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>

lib/internal/modules/cjs/loader.js

@@ -435,7 +435,7 @@ function resolveBasePath(basePath, exts, isMain, trailingSlash, request) {
 
 function trySelf(parentPath, isMain, request) {
   const { data: pkg, path: basePath } = readPackageScope(parentPath) || {};
-  if (!pkg || 'exports' in pkg === false) return false;
+  if (!pkg || pkg.exports === undefined) return false;
   if (typeof pkg.name !== 'string') return false;
 
   let expansion;