Fix typo lib/storage.js

Co-authored-by: arantes555 <arantes555@gmail.com>

lib/storage.js

@@ -272,7 +272,7 @@ const ensureDatafileIntegrityAsync = async (filename, mode = DEFAULT_FILE_MODE)
 }
 
 /**
- * Check if a file's parent directory of exists and create it on the fly if it is not the case.
+ * Check if a file's parent directory exists and create it on the fly if it is not the case.
  * @param {string} filename
  * @param {number} mode
  * @return {Promise<void>}