Fix exception on res.end(null) calls

fixes expressjs#75

Author: dougwilson

History.md

@@ -1,3 +1,8 @@
+unreleased
+==========
+
+  * Fix exception on `res.end(null)` calls
+
 1.7.5 / 2014-08-10
 ==================
 

index.js

@@ -193,7 +193,7 @@ function session(options){
       var ret;
       var sync = true;
 
-      if (chunk === undefined) {
+      if (chunk == null) {
         chunk = '';
       }
 

test/session.js

@@ -184,6 +184,16 @@ describe('session()', function(){
     .expect(200, 'Hello, world!', done);
   })
 
+  it('should handle res.end(null) calls', function (done) {
+    var server = createServer(null, function (req, res) {
+      res.end(null)
+    })
+
+    request(server)
+    .get('/')
+    .expect(200, '', done)
+  })
+
   describe('when response ended', function () {
     it('should have saved session', function (done) {
       var saved = false