cmd/clef: suppress fsnotify error if keydir not exists (ethereum#28160)

As the keydir will be automatically created after an account is created, no error message if the watcher is failed.

accounts/keystore/watch.go

@@ -20,6 +20,7 @@
 package keystore
 
 import (
+	"os"
 	"time"
 
 	"github.com/ethereum/go-ethereum/log"
@@ -77,7 +78,9 @@ func (w *watcher) loop() {
 	}
 	defer watcher.Close()
 	if err := watcher.Add(w.ac.keydir); err != nil {
-		logger.Warn("Failed to watch keystore folder", "err", err)
+		if !os.IsNotExist(err) {
+			logger.Warn("Failed to watch keystore folder", "err", err)
+		}
 		return
 	}