From acf5b6e284a848e0e7a7b283bc5b57a08afb3b72 Mon Sep 17 00:00:00 2001
From: Camden Dixie O'Brien <cdo@wip.sh>
Date: Sun, 15 Mar 2026 13:42:56 +0000
Subject: [PATCH] Handle failed def lookup in action_data()

---
 asm.js | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/asm.js b/asm.js
index 9fce033..38fe606 100644
--- a/asm.js
+++ b/asm.js
@@ -1009,9 +1009,16 @@ export class Assembler {
 
     action_data(action) {
         const data = this.data.at(-1).data;
-        const value = action.value != null
-              ? action.value
-              : this.le(this.lookup_def(action.symbol), action.size);
+        let value = action.value;
+        if (value == undefined) {
+            const raw = this.lookup_def(action.symbol);
+            if (raw == undefined) {
+                console.error(
+                    `ERROR: Unable to resolve symbol ${action.symbol}`);
+                return;
+            }
+            value = this.le(raw, action.size);
+        }
         data.push(...value);
         this.pos.addr += action.size;
     }