Timeout hint (#634)

lib/versionmanager.js

@@ -2,6 +2,7 @@
 const semver = require('semver');
 const _ = require('lodash');
 const cint = require('cint');
+const chalk = require('chalk');
 const semverutils = require('semver-utils');
 const ProgressBar = require('progress');
 const versionUtil = require('./version-util.js');
@@ -433,9 +434,16 @@ function queryVersions(packageMap, options = {}) {
                 pre: options.pre != null ? options.pre : versionUtil.isPre(packageMap[dep])
             }
         )).catch(err => {
-            if (err && (err.message || err).toString().match(/E404|ENOTFOUND|404 Not Found/i)) {
+            const errorMessage = err ? (err.message || err).toString() : '';
+            if (errorMessage.match(/E404|ENOTFOUND|404 Not Found/i)) {
                 return null;
             } else {
+
+                // print a hint about the --timeout option for network timeout errors
+                if (/(Response|network) timeout/i.test(errorMessage)) {
+                    console.error('\n\n' + chalk.red('FetchError: Request Timeout. npm-registry-fetch defaults to 30000 (30 seconds). Try setting the --timeout option (in milliseconds) to override this.') + '\n');
+                }
+
                 throw err;
             }
         }).then(result => {