From 0297eb726aa26a350d67eae238f7fcbaeda65bf6 Mon Sep 17 00:00:00 2001
From: jberg <jberg@users.noreply.github.com>
Date: Mon, 19 Aug 2019 09:10:46 -0700
Subject: [PATCH] Convert null MAKI objects to global NULL value (#866)

* Coerce null MAKI objects to 0

* use global NULL value
---
 modern/src/maki-interpreter/interpreter.js | 10 ++++++++--
 modern/src/maki-interpreter/variable.js    |  2 +-
 2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/modern/src/maki-interpreter/interpreter.js b/modern/src/maki-interpreter/interpreter.js
index f458e724..af99cb6f 100644
--- a/modern/src/maki-interpreter/interpreter.js
+++ b/modern/src/maki-interpreter/interpreter.js
@@ -161,11 +161,17 @@ export function* interpret(start, program, stack = []) {
         }
         const obj = popStackValue();
         const ret = obj[methodName](...methodArgs);
+        let value;
         if (isPromise(ret)) {
-          stack.push(yield ret);
+          value = yield ret;
         } else {
-          stack.push(ret);
+          value = ret;
         }
+        if (value === null) {
+          // variables[1] holds global NULL value
+          value = variables[1];
+        }
+        stack.push(value);
         break;
       }
       // callGlobal
diff --git a/modern/src/maki-interpreter/variable.js b/modern/src/maki-interpreter/variable.js
index 27c70a40..b52d5481 100644
--- a/modern/src/maki-interpreter/variable.js
+++ b/modern/src/maki-interpreter/variable.js
@@ -17,7 +17,7 @@ class Variable {
     if (this._unsubscribeFromValue != null) {
       this._unsubscribeFromValue();
     }
-    if (this.global && this.typeName === "OBJECT" && value !== null) {
+    if (this.global && this.typeName === "OBJECT" && value !== 0) {
       this._unsubscribeFromValue = value.js_listenToAll(
         (eventName, ...args) => {
           this._emitter.trigger(eventName.toLowerCase(), ...args);