Micro optimisation

tools/disk_cache/implementation.go

@@ -287,10 +287,13 @@ func (dc *DiskCache) add(key string, items map[string][]byte) (err error) {
 	for x, data := range items {
 		p := filepath.Join(base, x)
 		var before int64
+		exists := false
 		if s, err := os.Stat(p); err == nil {
 			before = s.Size()
+			exists = true
 		}
 		if len(data) == 0 {
+			if exists {
 				if err = os.Remove(p); err != nil {
 					if !os.IsNotExist(err) {
 						return
@@ -298,10 +301,13 @@ func (dc *DiskCache) add(key string, items map[string][]byte) (err error) {
 					err = nil
 				}
 				changed -= before
+			}
 		} else {
 			// unlink the file so that writing to it does not change a
 			// previously linked copy created by get()
+			if exists {
 				_ = os.Remove(p)
+			}
 			if err = os.WriteFile(p, data, 0o700); err != nil {
 				return
 			}