adjust fetch util

Author: AbhiPrasad

packages/browser/src/transports/fetch.ts

@@ -11,7 +11,7 @@ import { clearCachedFetchImplementation, getNativeFetchImplementation } from './
  */
 export function makeFetchTransport(
   options: BrowserTransportOptions,
-  nativeFetch: FetchImpl = getNativeFetchImplementation(),
+  nativeFetch: FetchImpl | undefined = getNativeFetchImplementation(),
 ): Transport {
   let pendingBodySize = 0;
   let pendingCount = 0;
@@ -41,6 +41,11 @@ export function makeFetchTransport(
       ...options.fetchOptions,
     };
 
+    if (!nativeFetch) {
+      clearCachedFetchImplementation();
+      return rejectedSyncPromise('No fetch implementation available');
+    }
+
     try {
       return nativeFetch(options.url, requestOptions).then(response => {
         pendingBodySize -= requestSize;

packages/browser/src/transports/utils.ts

@@ -45,7 +45,7 @@ export type FetchImpl = typeof fetch;
  * Firefox: NetworkError when attempting to fetch resource
  * Safari:  resource blocked by content blocker
  */
-export function getNativeFetchImplementation(): FetchImpl {
+export function getNativeFetchImplementation(): FetchImpl | undefined {
   if (cachedFetchImpl) {
     return cachedFetchImpl;
   }
@@ -75,7 +75,13 @@ export function getNativeFetchImplementation(): FetchImpl {
     }
   }
 
-  return (cachedFetchImpl = fetchImpl.bind(WINDOW));
+  try {
+    return (cachedFetchImpl = fetchImpl.bind(WINDOW));
+  } catch (e) {
+    // empty
+  }
+
+  return undefined;
   /* eslint-enable @typescript-eslint/unbound-method */
 }