serial.send won't depend on callback anymore

js/serial.js

@@ -148,7 +148,7 @@ var serial = {
                     self.bytes_sent += sendInfo.bytesSent;
 
                     // fire callback
-                    callback(sendInfo);
+                    if (callback) callback(sendInfo);
 
                     // remove data for current transmission form the buffer
                     self.output_buffer.shift();

manifest.json

@@ -1,7 +1,7 @@
 {
     "manifest_version": 2,
     "minimum_chrome_version": "36",
-    "version": "0.54.1",
+    "version": "0.54.2",
 
     "author": "cTn",
     "name": "Baseflight - Configurator",