fix: handle Discord gateway metadata fetch failures (#44397)

Merged via squash.

Prepared head SHA: edd17c0eff
Co-authored-by: jalehman <550978+jalehman@users.noreply.github.com>
Co-authored-by: jalehman <550978+jalehman@users.noreply.github.com>
Reviewed-by: @jalehman

src/infra/unhandled-rejections.test.ts

@@ -130,6 +130,13 @@ describe("isTransientNetworkError", () => {
     expect(isTransientNetworkError(error)).toBe(true);
   });
 
+  it("returns true for wrapped Discord upstream-connect parse failures", () => {
+    const error = new Error(
+      `Failed to get gateway information from Discord: Unexpected token 'u', "upstream connect error or disconnect/reset before headers. reset reason: overflow" is not valid JSON`,
+    );
+    expect(isTransientNetworkError(error)).toBe(true);
+  });
+
   it("returns false for non-network fetch-failed wrappers from tools", () => {
     const error = new Error("Web fetch failed (404): Not Found");
     expect(isTransientNetworkError(error)).toBe(false);

src/infra/unhandled-rejections.ts

@@ -61,6 +61,8 @@ const TRANSIENT_NETWORK_MESSAGE_SNIPPETS = [
   "network error",
   "network is unreachable",
   "temporary failure in name resolution",
+  "upstream connect error",
+  "disconnect/reset before headers",
   "tlsv1 alert",
   "ssl routines",
   "packet length too long",