fix(op_crate/fetch): infinite loop on fill headers (#10406)

Fixes a pesky bug in the fetch implementation where if the init part is
specified in `fetch` instead of the `Request` constructor, the
fillHeaders function receives two references to the same object, causing
it to append to the same list being iterated over.

1 files changed, 5 insertions, 2 deletions

diff --git a/op_crates/fetch/23_request.js b/op_crates/fetch/23_request.js
index 0e4bd2a3f..603a37a5f 100644
--- a/op_crates/fetch/23_request.js
+++ b/op_crates/fetch/23_request.js
@@ -247,11 +247,14 @@
 
       // 31.
       if (Object.keys(init).length > 0) {
-        let headers = headerListFromHeaders(this[_headers]);
+        let headers = headerListFromHeaders(this[_headers]).slice(
+          0,
+          headerListFromHeaders(this[_headers]).length,
+        );
         if (init.headers !== undefined) {
           headers = init.headers;
         }
-        headerListFromHeaders(this[_headers]).slice(
+        headerListFromHeaders(this[_headers]).splice(
           0,
           headerListFromHeaders(this[_headers]).length,
         );