Error for buttons without a configuration

index.js

@@ -34,6 +34,11 @@ client.on( 'newVerifiedButton', function( bdAddr ) {
  * BUTTON REACTIONS
  */
 function listenToButton( bdAddr ) {
+    if ( "object" !== typeof config.buttons[bdAddr] ) {
+        console.error( 'No configuration for button ' + bdAddr );
+        return;
+    }
+
     var cc = new FlicConnectionChannel( bdAddr );
     client.addConnectionChannel( cc );