Refactor onFrameNavigated tracing

Reduces nested levels.

common/frame_session.go

@@ -750,39 +750,47 @@ func (fs *FrameSession) onFrameNavigated(frame *cdp.Frame, initial bool) {
 
 	// Trace navigation only for the main frame.
 	// TODO: How will this affect sub frames such as iframes?
-	if isMainFrame := frame.ParentID == ""; isMainFrame {
-		_, fs.mainFrameSpan = TraceNavigation(
-			fs.ctx, fs.targetID.String(), frame.URL,
-			trace.WithAttributes(attribute.String("url", frame.URL)),
-		)
-
-		var (
-			spanID   = fs.mainFrameSpan.SpanContext().SpanID().String()
-			newFrame = fs.manager.getFrameByID(frame.ID)
-		)
-		// Set k6SpanId property in the page so it can be retrieved when pushing
-		// the Web Vitals events from the page execution context and used to
-		// correlate them with the navigation span to which they belong to.
-		if newFrame != nil {
-			// Executing a CDP command in the event parsing goroutine might deadlock in some cases.
-			// For example a deadlock happens if the content loaded in the frame that has navigated
-			// includes a JavaScript initiated dialog which we have to explicitly accept or dismiss
-			// (see onEventJavascriptDialogOpening). In that case our EvaluateGlobal call can't be
-			// executed, as the browser is waiting for us to accept/dismiss the JS dialog, but we
-			// can't act on that because the event parsing goroutine is stuck in onFrameNavigated.
-			// Because in this case the action is to set an attribute to the global object (window)
-			// it should be safe to just execute this in a separate goroutine.
-			go func() {
-				js := fmt.Sprintf("window.k6SpanId = '%s';", spanID)
-				err := newFrame.EvaluateGlobal(fs.ctx, js)
-				if err != nil {
-					fs.logger.Errorf(
-						"FrameSession:onFrameNavigated", "error on evaluating window.k6SpanId: %v", err,
-					)
-				}
-			}()
+	if isMainFrame := frame.ParentID == ""; !isMainFrame {
+		return
+	}
+
+	_, fs.mainFrameSpan = TraceNavigation(
+		fs.ctx, fs.targetID.String(), frame.URL,
+		trace.WithAttributes(attribute.String("url", frame.URL)),
+	)
+
+	var (
+		spanID   = fs.mainFrameSpan.SpanContext().SpanID().String()
+		newFrame = fs.manager.getFrameByID(frame.ID)
+	)
+
+	// Only set the k6SpanId reference if it's a new frame.
+	if newFrame == nil {
+		return
+	}
+
+	// Set k6SpanId property in the page so it can be retrieved when pushing
+	// the Web Vitals events from the page execution context and used to
+	// correlate them with the navigation span to which they belong to.
+	setSpanIDProp := func() {
+		js := fmt.Sprintf("window.k6SpanId = '%s';", spanID)
+		err := newFrame.EvaluateGlobal(fs.ctx, js)
+		if err != nil {
+			fs.logger.Errorf(
+				"FrameSession:onFrameNavigated", "error on evaluating window.k6SpanId: %v", err,
+			)
 		}
 	}
+
+	// Executing a CDP command in the event parsing goroutine might deadlock in some cases.
+	// For example a deadlock happens if the content loaded in the frame that has navigated
+	// includes a JavaScript initiated dialog which we have to explicitly accept or dismiss
+	// (see onEventJavascriptDialogOpening). In that case our EvaluateGlobal call can't be
+	// executed, as the browser is waiting for us to accept/dismiss the JS dialog, but we
+	// can't act on that because the event parsing goroutine is stuck in onFrameNavigated.
+	// Because in this case the action is to set an attribute to the global object (window)
+	// it should be safe to just execute this in a separate goroutine.
+	go setSpanIDProp()
 }
 
 func (fs *FrameSession) onFrameRequestedNavigation(event *cdppage.EventFrameRequestedNavigation) {