Fix exception when TCP connection drops abruptly

lib/cwmp.coffee

@@ -67,12 +67,13 @@ writeResponse = (sessionContext, res) ->
       res.headers['Content-Length'] = data.length
       sessionContext.httpResponse.writeHead(res.code, res.headers)
       sessionContext.httpResponse.end(data)
+      delete sessionContext.httpRequest
+      delete sessionContext.httpResponse
     )
   else
     res.headers['Content-Length'] = res.data.length
     sessionContext.httpResponse.writeHead(res.code, res.headers)
     sessionContext.httpResponse.end(res.data)
-
     delete sessionContext.httpRequest
     delete sessionContext.httpResponse
 
@@ -608,8 +609,6 @@ onConnection = (socket) ->
   socket.on('close', () ->
     sessions = currentSessions.get(socket)
     for sessionId, sessionContext of sessions
-      delete sessionContext.httpRequest
-      delete sessionContext.httpResponse
       session.serialize(sessionContext, (err, sessionContextString) ->
         return throwError(err) if err
         # TODO don't set if process is shutting down

lib/session.coffee

@@ -1599,20 +1599,15 @@ serialize = (sessionContext, callback) ->
 
     deviceData.push(e)
 
-  oldDeviceData = sessionContext.deviceData
-  oldSyncState = sessionContext.syncState
-  oldToLoad = sessionContext.toLoad
-
+  sessionContext = Object.assign({}, sessionContext)
   sessionContext.deviceData = deviceData
   delete sessionContext.syncState
   delete sessionContext.toLoad
+  delete sessionContext.httpRequest
+  delete sessionContext.httpResponse
 
   sessionContextString = JSON.stringify(sessionContext)
 
-  sessionContext.deviceData = oldDeviceData
-  sessionContext.syncState = oldSyncState
-  sessionContext.toLoad = oldToLoad
-
   return callback(null, sessionContextString)