actually propagate the error to be consistent with errors propagates by http.request

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

@@ -145,9 +145,16 @@ web_o = Object.keys(web_o).map(function(pass) {
     (options.buffer || req).pipe(proxyReq);
 
     proxyReq.on('response', function(proxyRes) {
-      if(server) { server.emit('proxyRes', proxyRes, req, res); }
-      for(var i=0; i < web_o.length; i++) {
-        if(web_o[i](req, res, proxyRes, options)) { break; }
+      var stop = false;
+      
+      if (server) { server.emit('proxyRes', proxyRes, req, res); }
+      for (var i=0; i < web_o.length; i++) {
+        try {
+          stop = web_o[i](req, res, proxyRes, options);
+        } catch(e) {
+          return proxyError(e);
+        }
+        if (stop) { break; }
       }
 
       // Allow us to listen when the proxy has completed

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

@@ -83,11 +83,7 @@ var redirectRegex = /^30(1|2|7|8)$/;
   function writeHeaders(req, res, proxyRes) {
     Object.keys(proxyRes.headers).forEach(function(key) {
       if (proxyRes.headers[key] != undefined) {
-        try {
-          res.setHeader(key, proxyRes.headers[key]);
-        } catch (e) {
-          // ignore invalid headers
-        }
+        res.setHeader(key, proxyRes.headers[key]);
       }
     });
   },