Typo in index.js

Fix a typo in index.js.

Author: joaomoreno

index.js

@@ -223,7 +223,7 @@ function getEndOfCentralDirectoryRecord(self) {
 }
 
 function validateMetadataPath(metadataPath, isDirectory) {
-  if (metadataPath === "") throw new Erorr("empty metadataPath");
+  if (metadataPath === "") throw new Error("empty metadataPath");
   if (metadataPath.indexOf("\\") !== -1) throw new Error("invalid characters in path: " + metadataPath);
   if (/^[a-zA-Z]:/.test(metadataPath) || /^\//.test(metadataPath)) throw new Error("absolute path: " + metadataPath);
   if (metadataPath.split("/").indexOf("..") !== -1) throw new Error("invalid relative path: " + metadataPath);