diff --git a/tracker/tracker/src/main/app/index.ts b/tracker/tracker/src/main/app/index.ts
index 8b2271619..2f9525164 100644
--- a/tracker/tracker/src/main/app/index.ts
+++ b/tracker/tracker/src/main/app/index.ts
@@ -233,10 +233,16 @@ export default class App {
     // For example - attachEventListener() called during dynamic <iframe> appearance
     this.commitCallbacks.push(cb)
   }
-  attachStartCallback(cb: StartCallback): void {
+  attachStartCallback(cb: StartCallback, useSafe = false): void {
+    if (useSafe) {
+      cb = this.safe(cb)
+    }
     this.startCallbacks.push(cb)
   }
-  attachStopCallback(cb: () => any): void {
+  attachStopCallback(cb: () => any, useSafe = false): void {
+    if (useSafe) {
+      cb = this.safe(cb)
+    }
     this.stopCallbacks.push(cb)
   }
   attachEventListener(
@@ -249,8 +255,8 @@ export default class App {
     if (useSafe) {
       listener = this.safe(listener)
     }
-    this.attachStartCallback(() => target.addEventListener(type, listener, useCapture))
-    this.attachStopCallback(() => target.removeEventListener(type, listener, useCapture))
+    this.attachStartCallback(() => target.addEventListener(type, listener, useCapture), useSafe)
+    this.attachStopCallback(() => target.removeEventListener(type, listener, useCapture), useSafe)
   }
 
   // TODO: full correct semantic
diff --git a/tracker/tracker/src/main/app/observer/top_observer.ts b/tracker/tracker/src/main/app/observer/top_observer.ts
index 47ba5fa10..5e4899692 100644
--- a/tracker/tracker/src/main/app/observer/top_observer.ts
+++ b/tracker/tracker/src/main/app/observer/top_observer.ts
@@ -61,7 +61,7 @@ export default class TopObserver extends Observer {
   private readonly contextCallbacks: Array<ContextCallback> = []
 
   // Attached once per Tracker instance
-  private readonly contextsSet: Set<Context> = new Set()
+  private readonly contextsSet: Set<Window> = new Set()
   attachContextCallback(cb: ContextCallback) {
     this.contextCallbacks.push(cb)
   }
@@ -105,11 +105,11 @@ export default class TopObserver extends Observer {
         currentWin &&
         // Sometimes currentWin.window is null (not in specification). Such window object is not functional
         currentWin === currentWin.window &&
-        !this.contextsSet.has(currentWin.window) // for each context callbacks called once per Tracker (TopObserver) instance
+        !this.contextsSet.has(currentWin) // for each context callbacks called once per Tracker (TopObserver) instance
       ) {
-        this.contextsSet.add(currentWin.window)
-        //+ https://github.com/microsoft/TypeScript/issues/41684
-        this.contextCallbacks.forEach((cb) => cb(currentWin.window))
+        this.contextsSet.add(currentWin)
+        //@ts-ignore https://github.com/microsoft/TypeScript/issues/41684
+        this.contextCallbacks.forEach((cb) => cb(currentWin))
         win = currentWin
       }
     })
diff --git a/tracker/tracker/src/webworker/BatchWriter.ts b/tracker/tracker/src/webworker/BatchWriter.ts
index f0d2ce5f2..252b07e5d 100644
--- a/tracker/tracker/src/webworker/BatchWriter.ts
+++ b/tracker/tracker/src/webworker/BatchWriter.ts
@@ -97,7 +97,7 @@ export default class BatchWriter {
     this.finaliseBatch()
     while (!this.writeWithSize(message)) {
       if (this.beaconSize === this.beaconSizeLimit) {
-        console.warn('OpenReplay: beacon size overflow. Skipping large message.', message)
+        console.warn('OpenReplay: beacon size overflow. Skipping large message.', message, this)
         this.encoder.reset()
         this.prepare()
         return