Fix Jellyfin Login (#76)

src/main/runtime/update/fetch-adapter.ts

@@ -4,6 +4,19 @@ export interface ElectronNetFetchLike {
   fetch: (url: string, init?: Record<string, unknown>) => Promise<FetchResponseLike>;
 }
 
+export type GlobalFetchLike = (url: string, init?: RequestInit) => Promise<FetchResponseLike>;
+
 export function createElectronNetFetch(net: ElectronNetFetchLike): FetchLike {
   return (url, init) => net.fetch(url, init);
 }
+
+function getGlobalFetch(): GlobalFetchLike {
+  if (typeof globalThis.fetch !== 'function') {
+    throw new Error('Global fetch is not available for updater requests.');
+  }
+  return globalThis.fetch.bind(globalThis) as GlobalFetchLike;
+}
+
+export function createGlobalFetch(fetchImpl?: GlobalFetchLike): FetchLike {
+  return (url, init) => (fetchImpl ?? getGlobalFetch())(url, init as RequestInit);
+}