[client] Fix errcheck findings from the latest golangci-lint (#8251)

client/iface/iface_close_test.go

@@ -12,6 +12,7 @@ import (
 	"golang.zx2c4.com/wireguard/tun/netstack"
 
 	"github.com/netbirdio/netbird/client/iface/device"
+	nbnetstack "github.com/netbirdio/netbird/client/iface/netstack"
 	"github.com/netbirdio/netbird/client/iface/udpmux"
 	"github.com/netbirdio/netbird/client/iface/wgaddr"
 	"github.com/netbirdio/netbird/client/iface/wgproxy"
@@ -62,6 +63,10 @@ func (fakeProxyFactory) Free() error             { return nil }
 // WGIface.GetDevice() which needs the same mutex. The fix is to drop
 // the lock before tun.Close() returns control.
 func TestWGIface_CloseReleasesMutexBeforeTunClose(t *testing.T) {
+	// Netstack mode skips the platform interface cleanup in Close, so only
+	// the mutex and tun close behavior is exercised.
+	t.Setenv(nbnetstack.EnvUseNetstackMode, "true")
+
 	tun := &fakeTunDevice{
 		closeStarted: make(chan struct{}),
 		unblockClose: make(chan struct{}),
@@ -105,7 +110,10 @@ func TestWGIface_CloseReleasesMutexBeforeTunClose(t *testing.T) {
 
 	close(tun.unblockClose)
 	select {
-	case <-closeDone:
+	case err := <-closeDone:
+		if err != nil {
+			t.Errorf("WGIface.Close() returned an error: %v", err)
+		}
 	case <-time.After(2 * time.Second):
 		t.Fatal("WGIface.Close() never returned after the tun was unblocked")
 	}

client/ssh/client/client.go

@@ -166,7 +166,8 @@ func (c *Client) ExecuteCommandWithIO(ctx context.Context, command string) error
 	case <-ctx.Done():
 		_ = session.Signal(ssh.SIGTERM)
 		select {
-		case <-done:
+		case err := <-done:
+			log.Debugf("session ended after SIGTERM: %v", err)
 			return ctx.Err()
 		case <-time.After(100 * time.Millisecond):
 			return ctx.Err()
@@ -205,7 +206,8 @@ func (c *Client) ExecuteCommandWithPTY(ctx context.Context, command string) erro
 	case <-ctx.Done():
 		_ = session.Signal(ssh.SIGTERM)
 		select {
-		case <-done:
+		case err := <-done:
+			log.Debugf("session ended after SIGTERM: %v", err)
 			return ctx.Err()
 		case <-time.After(100 * time.Millisecond):
 			return ctx.Err()

management/internals/server/server.go

@@ -335,7 +335,11 @@ func (s *BaseServer) Stop() error {
 	}
 
 	select {
-	case <-s.Errors():
+	case err := <-s.Errors():
+		if err != nil {
+			log.WithContext(ctx).Infof("stopped Management Service: %v", err)
+			return nil
+		}
 		log.WithContext(ctx).Infof("stopped Management Service")
 		return nil
 	case <-ctx.Done():