Pr/make web worker friendly

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@microsoft/fetch-event-source",
-  "version": "2.0.1",
+  "version": "2.0.3",
   "description": "A better API for making Event Source requests, with all the features of fetch()",
   "homepage": "https://github.com/Azure/fetch-event-source#readme",
   "repository": "github:Azure/fetch-event-source",

src/fetch.ts

@@ -74,20 +74,20 @@ export function fetchEventSource(input: RequestInfo, {
         let curRequestController: AbortController;
         function onVisibilityChange() {
             curRequestController.abort(); // close existing request on every visibility change
-            if (!document.hidden) {
+            if (!globalThis.document?.hidden) {
                 create(); // page is now visible again, recreate request.
             }
         }
 
-        if (!openWhenHidden) {
-            document.addEventListener('visibilitychange', onVisibilityChange);
+        if (globalThis.document && !openWhenHidden) {
+            globalThis.document?.addEventListener('visibilitychange', onVisibilityChange);
         }
 
         let retryInterval = DefaultRetryInterval;
         let retryTimer = 0;
         function dispose() {
-            document.removeEventListener('visibilitychange', onVisibilityChange);
-            window.clearTimeout(retryTimer);
+            globalThis.document?.removeEventListener('visibilitychange', onVisibilityChange);
+            globalThis.clearTimeout(retryTimer);
             curRequestController.abort();
         }
 
@@ -97,9 +97,12 @@ export function fetchEventSource(input: RequestInfo, {
             resolve(); // don't waste time constructing/logging errors
         });
 
-        const fetch = inputFetch ?? window.fetch;
+        const fetch = inputFetch ?? globalThis.fetch;
         const onopen = inputOnOpen ?? defaultOnOpen;
         async function create() {
+            if (curRequestController) {
+                curRequestController.abort();
+            }
             curRequestController = new AbortController();
             try {
                 const response = await fetch(input, {
@@ -131,8 +134,8 @@ export function fetchEventSource(input: RequestInfo, {
                     try {
                         // check if we need to retry:
                         const interval: any = onerror?.(err) ?? retryInterval;
-                        window.clearTimeout(retryTimer);
-                        retryTimer = window.setTimeout(create, interval);
+                        globalThis.clearTimeout(retryTimer);
+                        retryTimer = globalThis.setTimeout(create, interval);
                     } catch (innerErr) {
                         // we should not retry anymore:
                         dispose();