fix(fetch): fix stream handling in Safari by fallback to using a stream reader instead of an async iterator; (#6584)

lib/helpers/trackStream.js

@@ -17,14 +17,34 @@ export const streamChunk = function* (chunk, chunkSize) {
   }
 }
 
-export const readBytes = async function* (iterable, chunkSize, encode) {
-  for await (const chunk of iterable) {
-    yield* streamChunk(ArrayBuffer.isView(chunk) ? chunk : (await encode(String(chunk))), chunkSize);
+export const readBytes = async function* (iterable, chunkSize) {
+  for await (const chunk of readStream(iterable)) {
+    yield* streamChunk(chunk, chunkSize);
   }
 }
 
-export const trackStream = (stream, chunkSize, onProgress, onFinish, encode) => {
-  const iterator = readBytes(stream, chunkSize, encode);
+const readStream = async function* (stream) {
+  if (stream[Symbol.asyncIterator]) {
+    yield* stream;
+    return;
+  }
+
+  const reader = stream.getReader();
+  try {
+    for (;;) {
+      const {done, value} = await reader.read();
+      if (done) {
+        break;
+      }
+      yield value;
+    }
+  } finally {
+    await reader.cancel();
+  }
+}
+
+export const trackStream = (stream, chunkSize, onProgress, onFinish) => {
+  const iterator = readBytes(stream, chunkSize);
 
   let bytes = 0;
   let done;