From cd7e42f0b6e9ad0ddd6f796b543017140409173a Mon Sep 17 00:00:00 2001
From: Jack Baker <jack.baker@exodusintel.com>
Date: Mon, 25 Apr 2022 20:35:36 -0700
Subject: [PATCH] Fix export object retrieval in WebAssembly.instantiate()

---
 content/init.js | 20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/content/init.js b/content/init.js
index 9cc0fbd..43b056c 100644
--- a/content/init.js
+++ b/content/init.js
@@ -825,20 +825,26 @@ const webAssemblyInstantiateHook = function(inObject, importObject = {}) {
 
     return new Promise(function(resolve, reject) {
         oldWebAssemblyInstantiate(instrumentedObject, importObject).then(function(instanceObject) {
+            let instance = instanceObject;
+
+            if (typeof instanceObject.instance !== "undefined") {
+                instance = instanceObject.instance;
+            }
+
             if (typeof memoryDescriptor !== "undefined" && memoryDescriptor.type === "export") {
-                memoryInstance = getMemoryFromObject(instanceObject.exports, memoryDescriptor);
+                let exportObject = instance.exports;
+
+                if (typeof exportObject !== "object") {
+                    colorError("WebAssembly.instantiate() failed to retrieve export object for instantiated module");
+                }
+
+                memoryInstance = getMemoryFromObject(exportObject, memoryDescriptor);
             }
 
             if (!(memoryInstance instanceof WebAssembly.Memory)) {
                 colorError("WebAssembly.instantiate() failed to retrieve a WebAssembly.Memory object");
             }
 
-            let instance = instanceObject;
-
-            if (typeof instanceObject.instance !== "undefined") {
-                instance = instanceObject.instance;
-            }
-
             cetus = new Cetus({
                 memory: memoryInstance,
                 watchpointExports: [instance.exports.addWatch],