Fix frame session bug on browser close

Browser close happens and then we keep processing events
from CDP. Instead of doing that, now we first try to
kill the browser process and immediately tell CDP to
close the browser. This way CDP stops emitting us more
events.

We also skip errors from FrameSession if browser is
already closed.

Author: inancgumus

common/browser.go

@@ -346,16 +346,21 @@ func (b *Browser) Close() {
 		b.logger.Debugf("Browser:Close", "already in a closing state")
 		return
 	}
-	b.browserProc.GracefulClose()
-	defer b.browserProc.Terminate()
+
+	atomic.CompareAndSwapInt64(&b.state, b.state, BrowserStateClosed)
 
 	action := cdpbrowser.Close()
 	if err := action.Do(cdp.WithExecutor(b.ctx, b.conn)); err != nil {
 		if _, ok := err.(*websocket.CloseError); !ok {
 			k6Throw(b.ctx, "unable to execute %T: %v", action, err)
 		}
 	}
-	atomic.CompareAndSwapInt64(&b.state, b.state, BrowserStateClosed)
+
+	// terminate the browser process early on, then tell the CDP
+	// afterwards. this will take a little bit of time, and CDP
+	// will stop emitting events.
+	b.browserProc.GracefulClose()
+	b.browserProc.Terminate()
 }
 
 // Contexts returns list of browser contexts

common/frame_session.go

@@ -805,8 +805,10 @@ func (fs *FrameSession) onAttachedToTarget(event *target.EventAttachedToTarget)
 			fs.session.id, fs.targetID, event.SessionID,
 			event.TargetInfo.TargetID, event.TargetInfo.BrowserContextID,
 			event.TargetInfo.Type, err)
-		// If we're no longer connected to browser, then ignore WebSocket errors
-		if !fs.page.browserCtx.browser.connected && strings.Contains(err.Error(), "websocket: close 1006 (abnormal closure)") {
+		// ignore errors if we're no longer connected to browser
+		// this happens when there is no browser but we still want to
+		// attach a frame to it.
+		if !fs.page.browserCtx.browser.IsConnected() {
 			return
 		}
 		// Ignore context canceled error to gracefuly handle shutting down
@@ -843,8 +845,10 @@ func (fs *FrameSession) onAttachedToTarget(event *target.EventAttachedToTarget)
 	// Handle new worker
 	w, err := NewWorker(fs.ctx, session, targetID, event.TargetInfo.URL)
 	if err != nil {
-		if !fs.page.browserCtx.browser.connected && strings.Contains(err.Error(), "websocket: close 1006 (abnormal closure)") {
-			// If we're no longer connected to browser, then ignore WebSocket errors
+		// ignore errors if we're no longer connected to browser
+		// this happens when there is no browser but we still want to
+		// attach a worker to it.
+		if !fs.page.browserCtx.browser.connected {
 			return
 		}
 		select {