Make atomic file replacement crash durable

internal/fileops/sync_directory_unsupported.go

@@ -2,6 +2,11 @@
 
 package fileops
 
-func syncDirectory(string) error {
-	return checkAtomicDirectoryPromotionSupport()
+import (
+	"fmt"
+	"runtime"
+)
+
+func syncDirectory(path string) error {
+	return fmt.Errorf("%w for %q on %s", ErrDirectorySyncUnsupported, path, runtime.GOOS)
 }