fix: skip disks that are offline when healing the drives (#12931)

cmd/format-erasure.go

@@ -705,10 +705,12 @@ func saveUnformattedFormat(ctx context.Context, storageDisks []StorageAPI, forma
 		if format == nil {
 			continue
 		}
+		if storageDisks[index] != nil && storageDisks[index].IsOnline() {
 			if err := saveFormatErasure(storageDisks[index], format, true); err != nil {
 				return err
 			}
 		}
+	}
 	return nil
 }