Handle connection error at start an application

This change will reconnect to fluentd, but following error occurs
while reconnecting:

> logger-node/node_modules/fluent-logger/node_modules/readable-stream/lib/_stream_writable.js:491
>   cb();
>   ^
>
> TypeError: cb is not a function
>     at afterWrite (/logger-node/node_modules/fluent-logger/node_modules/readable-stream/lib/_stream_writable.js:491:3)
>     at onwrite (/logger-node/node_modules/fluent-logger/node_modules/readable-stream/lib/_stream_writable.js:483:7)
>     at WritableState.onwrite (/logger-node/node_modules/fluent-logger/node_modules/readable-stream/lib/_stream_writable.js:180:5)
>     at sender.emit (/logger-node/node_modules/fluent-logger/lib/winston.js:46:21)
>     at callbacks.forEach (/logger-node/node_modules/fluent-logger/lib/sender.js:431:23)
>     at Array.forEach (<anonymous>)
>     at _socket.write (/logger-node/node_modules/fluent-logger/lib/sender.js:430:19)
>     at afterWrite (_stream_writable.js:480:3)
>     at process._tickCallback (internal/process/next_tick.js:63:19)

See also nodejs/node#23895

Signed-off-by: Kenji Okimoto <[email protected]>

Author: okkez

lib/sender.js

@@ -104,7 +104,8 @@ class FluentSender {
     }
 
     this._push(tag, timestamp, data, callback);
-    this._connect(() => {
+    this._connect((error) => {
+      error && callback && callback(error);
       this._flushSendQueue();
     });
   }
@@ -206,9 +207,9 @@ class FluentSender {
     this._connecting = true;
     process.nextTick(() => {
       if (this._socket === null) {
-        this._doConnect(() => {
+        this._doConnect((error) => {
           this._connecting = false;
-          callback();
+          callback(error);
         });
       } else {
         if (!this._socket.writable) {
@@ -232,7 +233,7 @@ class FluentSender {
       let errorHandler = (err) => {
         if (this._socket) {
           this._disconnect();
-          this._handleEvent('error', err);
+          this._handleEvent('error', err, callback);
         }
       };
       this._socket.on('error', errorHandler);