fix dump non-exist log directory (#9818)

cmd/dump.go

@@ -151,9 +151,11 @@ func runDump(ctx *cli.Context) error {
 		}
 	}
 
+	if com.IsExist(setting.LogRootPath) {
 		if err := z.AddDir("log", setting.LogRootPath); err != nil {
 			fatal("Failed to include log: %v", err)
 		}
+	}
 
 	if err = z.Close(); err != nil {
 		_ = os.Remove(fileName)