From 167fe5f758b135bcf8750779e6d3c389199ac5f1 Mon Sep 17 00:00:00 2001
From: Karl Seguin <k@openmymind.io>
Date: Mon, 2 Jun 2025 23:27:29 +0800
Subject: [PATCH] Guard against null object when trying to fetch a function

---
 src/browser/dom/event_target.zig | 6 ++++++
 src/runtime/js.zig               | 8 ++++++++
 2 files changed, 14 insertions(+)

diff --git a/src/browser/dom/event_target.zig b/src/browser/dom/event_target.zig
index acb6e934..34836fba 100644
--- a/src/browser/dom/event_target.zig
+++ b/src/browser/dom/event_target.zig
@@ -222,4 +222,10 @@ test "Browser.DOM.EventTarget" {
         .{ "content.dispatchEvent(new Event('he'));", null },
         .{ "obj1.calls", "1" },
     }, .{});
+
+    // doesn't crash on null receiver
+    try runner.testCases(&.{
+        .{ "content.addEventListener('he2', null);", null },
+        .{ "content.dispatchEvent(new Event('he2'));", null },
+    }, .{});
 }
diff --git a/src/runtime/js.zig b/src/runtime/js.zig
index a9ee587c..89fb4aff 100644
--- a/src/runtime/js.zig
+++ b/src/runtime/js.zig
@@ -1400,7 +1400,11 @@ pub fn Env(comptime State: type, comptime WebApis: type) type {
             }
 
             pub fn getFunction(self: JsObject, name: []const u8) !?Function {
+                if (self.isNullOrUndefined()) {
+                    return null;
+                }
                 const scope = self.scope;
+
                 const js_name = v8.String.initUtf8(scope.isolate, name);
 
                 const js_value = try self.js_obj.getValue(scope.context, js_name.toName());
@@ -1409,6 +1413,10 @@ pub fn Env(comptime State: type, comptime WebApis: type) type {
                 }
                 return try scope.createFunction(js_value);
             }
+
+            pub fn isNullOrUndefined(self: JsObject) bool {
+                return self.js_obj.toValue().isNullOrUndefined();
+            }
         };
 
         // This only exists so that we know whether a function wants the opaque