[client] Fix shutdown blocking on stuck ICE agent close (#4780)

client/internal/peer/ice/agent.go

@@ -22,6 +22,8 @@ const (
 	iceFailedTimeoutDefault       = 6 * time.Second
 	// iceRelayAcceptanceMinWaitDefault is the same as in the Pion ICE package
 	iceRelayAcceptanceMinWaitDefault = 2 * time.Second
+	// iceAgentCloseTimeout is the maximum time to wait for ICE agent close to complete
+	iceAgentCloseTimeout = 3 * time.Second
 )
 
 type ThreadSafeAgent struct {
@@ -32,7 +34,17 @@ type ThreadSafeAgent struct {
 func (a *ThreadSafeAgent) Close() error {
 	var err error
 	a.once.Do(func() {
-		err = a.Agent.Close()
+		done := make(chan error, 1)
+		go func() {
+			done <- a.Agent.Close()
+		}()
+
+		select {
+		case err = <-done:
+		case <-time.After(iceAgentCloseTimeout):
+			log.Warnf("ICE agent close timed out after %v, proceeding with cleanup", iceAgentCloseTimeout)
+			err = nil
+		}
 	})
 	return err
 }