From a054b42fa2515ed331ed1d0d89bea138ff43afa9 Mon Sep 17 00:00:00 2001
From: Alon Zakai <azakai@google.com>
Date: Tue, 28 Jul 2026 08:49:12 -0700
Subject: [PATCH] fix

---
 src/wasm/wasm-debug.cpp | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/wasm/wasm-debug.cpp b/src/wasm/wasm-debug.cpp
index c9d3e533311..b624f1ae143 100644
--- a/src/wasm/wasm-debug.cpp
+++ b/src/wasm/wasm-debug.cpp
@@ -436,8 +436,12 @@ struct AddrExprMap {
   void add(Expression* expr, const BinaryLocations::Span span) {
     assert(!startMap.contains(span.start));
     startMap[span.start] = expr;
-    assert(!endMap.contains(span.end));
-    endMap[span.end] = expr;
+    // The end may be 0, which means we never noted an end for this expression.
+    // TODO: We are likely dropping some debug info in wasm-ir-builder.cpp
+    if (span.end) {
+      assert(!endMap.contains(span.end));
+      endMap[span.end] = expr;
+    }
   }
 
   void add(Expression* expr,