fix(pi-devin): observe errored stream cancel rejection in reader teardown

src/stream.ts

@@ -400,7 +400,11 @@ async function* streamChatEvents(args: {
       // ignore
     }
     try {
-      void resp.body?.cancel();
+      // cancel() on an already-errored stream rejects with the stored
+      // error (e.g. undici TypeError("terminated") after the server drops
+      // the socket). try/catch cannot observe that rejection, so swallow
+      // it explicitly or it escapes as an uncaughtException and kills pi.
+      void resp.body?.cancel()?.catch(() => {});
     } catch {
       // ignore
     }