From 2eaf998e8a31ab30c89fd42cd1c75a4d7ce0cdb0 Mon Sep 17 00:00:00 2001
From: Marcelo Bottoni <marcelo.bottoni.85@gmail.com>
Date: Tue, 3 Feb 2026 17:07:18 -0300
Subject: [PATCH] fix: prevent adding events to closed StreamController

Add isClosed checks to DataStreamController's write() and error() methods
to prevent "Bad state: Cannot add event after closing" exception.

This error occurs when a participant disconnects and
validateParticipantHasNoActiveDataStreams() tries to send errors to
stream controllers that have already been closed.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
---
 lib/src/types/data_stream.dart | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/lib/src/types/data_stream.dart b/lib/src/types/data_stream.dart
index a5963ff54..5bad84795 100644
--- a/lib/src/types/data_stream.dart
+++ b/lib/src/types/data_stream.dart
@@ -161,9 +161,17 @@ class DataStreamController<T extends DataStream_Chunk> {
 
   Future<void> close() => streamController.close();
 
-  void write(T chunk) => streamController.add(chunk);
+  void write(T chunk) {
+    if (!streamController.isClosed) {
+      streamController.add(chunk);
+    }
+  }
 
-  void error(DataStreamError error) => streamController.addError(error);
+  void error(DataStreamError error) {
+    if (!streamController.isClosed) {
+      streamController.addError(error);
+    }
+  }
 }
 
 class ByteStreamInfo extends BaseStreamInfo {