Fixed node-fetch for Safari (todo: push this fix upstream to node-fetch).

packages/web/src.ts/index.ts

@@ -1,6 +1,7 @@
 "use strict";
 
-import { default as fetch } from "node-fetch";
+import { default as _fetch, Response, RequestInfo, RequestInit } from "node-fetch";
+const fetch: (url: RequestInfo, options: RequestInit) => Promise<Response> = _fetch.bind(global);
 
 import { encode as base64Encode } from "@ethersproject/base64";
 import * as errors from "@ethersproject/errors";