fix: [cron] prevent error to be stored in cache

cron/lib/common

@@ -71,7 +71,9 @@ cron:get_config() {
             fi
             cron:get_config "$value" || return 1
             ;;
-    esac > "$cache_file"
+    esac > "$cache_file.tmp"
+
+    mv -v "$cache_file.tmp" "$cache_file" >&2
 
     ## if cache file is empty, this is an error
     if [ ! -s "$cache_file" ]; then