From 6def9b018c6b4c87410e870f0a5d0469ba50d637 Mon Sep 17 00:00:00 2001
From: Max Shawabkeh <max99x@gmail.com>
Date: Sun, 1 Sep 2024 21:56:33 -0700
Subject: [PATCH] Fix hang when doing s += None. (#1297)

Co-authored-by: max99x <mshawabkeh@jamandtea.studio>
---
 python/sglang/lang/interpreter.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/python/sglang/lang/interpreter.py b/python/sglang/lang/interpreter.py
index 91f48456a..2f8ea7e78 100644
--- a/python/sglang/lang/interpreter.py
+++ b/python/sglang/lang/interpreter.py
@@ -855,6 +855,8 @@ class ProgramState:
         return self.stream_executor.get_meta_info(name)
 
     def __iadd__(self, other):
+        if other is None:
+            raise ValueError("Tried to append None to state.")
         self.stream_executor.submit(other)
         return self