Clean up orphan ReadableStream remaining after retry (#650)

source/core/Ky.ts

@@ -35,6 +35,8 @@ export class Ky {
 
 			// Delay the fetch so that body method shortcuts can set the Accept header
 			await Promise.resolve();
+			// Before using ky.request, _fetch clones a new Request for retries preparation.
+			// If retry is not needed, close the original Request ReadableStream for memory safety.
 			let response = await ky._fetch();
 
 			for (const hook of ky._options.hooks.afterResponse) {
@@ -63,6 +65,10 @@ export class Ky {
 				throw error;
 			}
 
+			// Now, it can be determined that a retry is not needed,
+			// close the ReadableStream of the ky.request.
+			await ky.request.body?.cancel();
+
 			// If `onDownloadProgress` is passed, it uses the stream API internally
 			/* istanbul ignore next */
 			if (ky._options.onDownloadProgress) {