avoid close 'nil' panics if any (#18890)

brings a generic implementation that
prints a stack trace for 'nil' channel
closes(), if not safely closes it.

internal/dsync/drwmutex.go

@@ -26,6 +26,7 @@ import (
 	"sync"
 	"time"
 
+	xioutil "github.com/minio/minio/internal/ioutil"
 	"github.com/minio/minio/internal/mcontext"
 	"github.com/minio/pkg/v2/console"
 	"github.com/minio/pkg/v2/env"
@@ -406,7 +407,7 @@ func refreshLock(ctx context.Context, ds *Dsync, id, source string, quorum int)
 	// We may have some unused results in ch, release them async.
 	go func() {
 		wg.Wait()
-		close(ch)
+		xioutil.SafeClose(ch)
 		for range ch {
 		}
 	}()
@@ -528,7 +529,7 @@ func lock(ctx context.Context, ds *Dsync, locks *[]string, id, source string, is
 	// We may have some unused results in ch, release them async.
 	go func() {
 		wg.Wait()
-		close(ch)
+		xioutil.SafeClose(ch)
 		for grantToBeReleased := range ch {
 			if grantToBeReleased.isLocked() {
 				// release abandoned lock