From a6b7474a6bd23bbceebbd4a0e1d941768572a1c0 Mon Sep 17 00:00:00 2001
From: Toad06 <gd.productions@laposte.net>
Date: Sun, 20 Dec 2020 16:06:50 +0100
Subject: [PATCH] web: Prevent crashes with external libraries

---
 web/packages/core/src/js-polyfills.ts | 53 +++++++++++++++++++++++++++
 web/packages/core/src/load-ruffle.ts  | 13 ++++++-
 2 files changed, 65 insertions(+), 1 deletion(-)
 create mode 100644 web/packages/core/src/js-polyfills.ts

diff --git a/web/packages/core/src/js-polyfills.ts b/web/packages/core/src/js-polyfills.ts
new file mode 100644
index 000000000..93d0f218e
--- /dev/null
+++ b/web/packages/core/src/js-polyfills.ts
@@ -0,0 +1,53 @@
+/* eslint @typescript-eslint/no-explicit-any: "off" */
+
+/**
+ * Polyfills the `Array.prototype.reduce` method.
+ *
+ * Production steps of ECMA-262, Edition 5, 15.4.4.21
+ * Reference: https://es5.github.io/#x15.4.4.21
+ * https://tc39.github.io/ecma262/#sec-array.prototype.reduce
+ *
+ */
+export function setArrayPrototypeReduce(): void {
+    Object.defineProperty(Array.prototype, "reduce", {
+        value: function (...args: any) {
+            const callback = args[0];
+            if (this === null) {
+                throw new TypeError(
+                    "Array.prototype.reduce called on null or undefined"
+                );
+            }
+            if (typeof callback !== "function") {
+                throw new TypeError(`${callback} is not a function`);
+            }
+
+            const o = Object(this);
+            const len = o.length >>> 0;
+            let k = 0;
+            let value;
+
+            if (args.length >= 2) {
+                value = args[1];
+            } else {
+                while (k < len && !(k in o)) {
+                    k++;
+                }
+                if (k >= len) {
+                    throw new TypeError(
+                        "Reduce of empty array with no initial value"
+                    );
+                }
+                value = o[k++];
+            }
+
+            while (k < len) {
+                if (k in o) {
+                    value = callback(value, o[k], k, o);
+                }
+                k++;
+            }
+
+            return value;
+        },
+    });
+}
diff --git a/web/packages/core/src/load-ruffle.ts b/web/packages/core/src/load-ruffle.ts
index 91bc5a36d..c37461a3d 100644
--- a/web/packages/core/src/load-ruffle.ts
+++ b/web/packages/core/src/load-ruffle.ts
@@ -6,6 +6,8 @@
 
 import { Ruffle } from "../pkg/ruffle_web";
 
+import { setArrayPrototypeReduce } from "./js-polyfills";
+
 /**
  * Load ruffle from an automatically-detected location.
  *
@@ -17,12 +19,21 @@ import { Ruffle } from "../pkg/ruffle_web";
  * instances.
  */
 async function fetchRuffle(): Promise<{ new (...args: any[]): Ruffle }> {
+    if (
+        typeof Array.prototype.reduce !== "function" ||
+        Array.prototype.reduce.toString().indexOf("[native code]") === -1
+    ) {
+        // Some external libraries override the `Array.prototype.reduce` method in a way
+        // that causes Webpack to crash (#1507, #1865), so we need to override it again.
+        setArrayPrototypeReduce();
+    }
+
     try {
         // If ruffleRuntimePath is defined then we are executing inside the extension
         // closure. In that case, we configure our local Webpack instance.
         __webpack_public_path__ = ruffleRuntimePath + "dist/";
     } catch (e) {
-        // Checking an undefined closure variable usually throws ReferencError,
+        // Checking an undefined closure variable usually throws ReferenceError,
         // so we need to catch it here and continue onward.
         if (!(e instanceof ReferenceError)) {
             throw e;