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.

cmd/erasure-decode.go

@@ -25,6 +25,7 @@ import (
 	"sync"
 	"sync/atomic"
 
+	xioutil "github.com/minio/minio/internal/ioutil"
 	"github.com/minio/minio/internal/logger"
 )
 
@@ -118,7 +119,7 @@ func (p *parallelReader) Read(dst [][]byte) ([][]byte, error) {
 	}
 
 	readTriggerCh := make(chan bool, len(p.readers))
-	defer close(readTriggerCh) // close the channel upon return
+	defer xioutil.SafeClose(readTriggerCh) // close the channel upon return
 
 	for i := 0; i < p.dataBlocks; i++ {
 		// Setup read triggers for p.dataBlocks number of reads so that it reads in parallel.