Added check to passes/web-outgoing.js to make sure the header being set is not undefined, which should be the only falsey value that could accidently show up and break that call. This fixes windows NTLM auth issues behind http-proxy.

Author: merpnderp

lib/http-proxy/passes/web-outgoing.js

@@ -82,7 +82,9 @@ var redirectRegex = /^30(1|2|7|8)$/;
    */
   function writeHeaders(req, res, proxyRes) {
     Object.keys(proxyRes.headers).forEach(function(key) {
-      res.setHeader(key, proxyRes.headers[key]);
+      if(proxyRes.headers[key] != undefined){
+        res.setHeader(key, proxyRes.headers[key]);
+      }
     });
   },