From 27240795d51ede5daa1e20194da80f1634aa0591 Mon Sep 17 00:00:00 2001
From: Timo Stamm <ts@timostamm.de>
Date: Fri, 3 Jun 2022 21:12:40 +0200
Subject: [PATCH] Guard access of response.type to support Cloudflare Workers

This is #321, but applied to the grpcweb-transport as well.

All tests pass locally.
---
 CHANGELOG.md                                      |  6 +++++-
 packages/grpcweb-transport/src/grpc-web-format.ts | 10 +++++++++-
 packages/twirp-transport/src/twirp-transport.ts   |  8 +++++++-
 3 files changed, 21 insertions(+), 3 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4f5e02a0..8b044ec2 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,10 @@
 ### unreleased changes
 
-none
+
+Bug fixes:
+
+- Guard access of response.type to support Cloudflare Workers, see #321  
+  Thanks to @mikeylemmon for the fix!
 
 
 ### v2.6.0
diff --git a/packages/grpcweb-transport/src/grpc-web-format.ts b/packages/grpcweb-transport/src/grpc-web-format.ts
index d9db719c..bda6f55b 100644
--- a/packages/grpcweb-transport/src/grpc-web-format.ts
+++ b/packages/grpcweb-transport/src/grpc-web-format.ts
@@ -86,13 +86,21 @@ export function readGrpcWebResponseHeader(headers: HttpHeaders, httpStatus: numb
 export function readGrpcWebResponseHeader(headersOrFetchResponse: HttpHeaders | Response, httpStatus?: number, httpStatusText?: string): [GrpcStatusCode, string | undefined, RpcMetadata] {
     if (arguments.length === 1) {
         let fetchResponse = headersOrFetchResponse as Response;
-        switch (fetchResponse.type) {
+
+        // Cloudflare Workers throw when the type property of a fetch response
+        // is accessed, so wrap access with try/catch. See:
+        // * https://developers.cloudflare.com/workers/runtime-apis/response/#properties
+        // * https://github.com/cloudflare/miniflare/blob/72f046e/packages/core/src/standards/http.ts#L646
+        let responseType
+        try { responseType = fetchResponse.type } catch {}
+        switch (responseType) {
             case "error":
             case "opaque":
             case "opaqueredirect":
                 // see https://developer.mozilla.org/en-US/docs/Web/API/Response/type
                 throw new RpcError(`fetch response type ${fetchResponse.type}`, GrpcStatusCode[GrpcStatusCode.UNKNOWN]);
         }
+
         return readGrpcWebResponseHeader(
             fetchHeadersToHttp(fetchResponse.headers),
             fetchResponse.status,
diff --git a/packages/twirp-transport/src/twirp-transport.ts b/packages/twirp-transport/src/twirp-transport.ts
index bb3376b3..c3e0ee15 100644
--- a/packages/twirp-transport/src/twirp-transport.ts
+++ b/packages/twirp-transport/src/twirp-transport.ts
@@ -58,7 +58,13 @@ export class TwirpFetchTransport implements RpcTransport {
 
                 defHeader.resolve(parseMetadataFromResponseHeaders(fetchResponse.headers));
 
-                switch (fetchResponse.type) {
+                // Cloudflare Workers throw when the type property of a fetch response
+                // is accessed, so wrap access with try/catch. See:
+                // * https://developers.cloudflare.com/workers/runtime-apis/response/#properties
+                // * https://github.com/cloudflare/miniflare/blob/72f046e/packages/core/src/standards/http.ts#L646
+                let responseType
+                try { responseType = fetchResponse.type } catch {}
+                switch (responseType) {
                     case "error":
                     case "opaque":
                     case "opaqueredirect":