improving browser detection

src/index.ts

@@ -1,6 +1,6 @@
 import { Observable, Lock } from "@hibas123/utils";
 //this references global on node and window in browser
-const fetch = this.fetch ? this.fetch : require("cross-fetch").default;
+const fetch = typeof window !== "undefined" && typeof window.fetch !== undefined ? window.fetch : require("cross-fetch").default;
 
 export interface IFileVersion {
    version: string;