fix: Update Request to work with ReadableStream polyfills (#164)

* Update Request to work with ReadableStream polyfills

Some web frameworks (like Remix) inject polyfills for ReadableStream and this change makes sure that the server will work correctly with those polyfills.

* Update response.ts to work with readablestream polyfill

* lint and format

* fixing types

src/request.ts

@@ -31,7 +31,8 @@ export class Request extends GlobalRequest {
     if (typeof input === 'object' && getRequestCache in input) {
       input = (input as any)[getRequestCache]()
     }
-    if (options?.body instanceof ReadableStream) {
+    // Check if body is ReadableStream like. This makes it compatbile with ReadableStream polyfills.
+    if (typeof (options?.body as ReadableStream)?.getReader !== 'undefined') {
       // node 18 fetch needs half duplex mode when request body is stream
       // if already set, do nothing since a Request object was passed to the options or explicitly set by the user.
       ;(options as any).duplex ??= 'half'

src/response.ts

@@ -40,7 +40,7 @@ export class Response {
       this.#init = init
     }
 
-    if (typeof body === 'string' || body instanceof ReadableStream) {
+    if (typeof body === 'string' || typeof (body as ReadableStream)?.getReader !== 'undefined') {
       let headers = (init?.headers || { 'content-type': 'text/plain; charset=UTF-8' }) as
         | Record<string, string>
         | Headers