sdk: only send events if we have any

packages/sdk/index.ts

@@ -111,10 +111,13 @@ class Batcher<T extends any> {
     if(this.timer) {
       clearTimeout(this.timer)
     }
+
+    if(this.queue.length > 0) {
       this.callback(this.queue)
       this.queue = []
     }
   }
+}
 
 export class Mixan {
   private fetch: Fetcher