fix: avoid agent runLoop exiting due to ws ping (#8852)

agent/agent.go

@@ -236,7 +236,9 @@ func (a *agent) runLoop(ctx context.Context) {
 		if err == nil {
 			continue
 		}
-		if errors.Is(err, context.Canceled) {
+		if ctx.Err() != nil {
+			// Context canceled errors may come from websocket pings, so we
+			// don't want to use `errors.Is(err, context.Canceled)` here.
 			return
 		}
 		if a.isClosed() {