From 784ee9de98fa3ecf321982541d89c792dbecfc35 Mon Sep 17 00:00:00 2001
From: Feross Aboukhadijeh <feross@feross.org>
Date: Mon, 21 Jun 2021 19:51:07 -0700
Subject: [PATCH] fix for browsers that don't support ?. syntax

---
 lib/transform-stream.js | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/lib/transform-stream.js b/lib/transform-stream.js
index 0032c9e..ad63c1a 100644
--- a/lib/transform-stream.js
+++ b/lib/transform-stream.js
@@ -7,7 +7,7 @@
  * result.done is a promise that fulfills or rejects once the stream is done.
  * Includes a shim for environments where TransformStream is not available.
  */
-export function transformStream (sourceReadable, transformer) {
+export function transformStream (sourceReadable, transformer = {}) {
   let transformedReadable
   let done
 
@@ -47,7 +47,7 @@ class TransformStreamSource {
   }
 
   async start (controller) {
-    if (this.transformer?.start) {
+    if (this.transformer.start) {
       try {
         await this.transformer.start(controller)
       } catch (err) {
@@ -71,14 +71,14 @@ class TransformStreamSource {
       try {
         const data = await this.reader.read()
         if (data.done) {
-          if (this.transformer?.flush) {
+          if (this.transformer.flush) {
             await this.transformer.flush(controller)
           }
           controller.close()
           this.resolveDone()
           return
         }
-        if (this.transformer?.transform) {
+        if (this.transformer.transform) {
           await this.transformer.transform(data.value, wrappedController)
         } else {
           wrappedController.enqueue(data.value)