Fix toString for proxies

lib/extension.js

@@ -136,14 +136,40 @@
 		}
 	};
 	
+	const proxies = new Map();
+	const changedToStrings = new WeakMap();
 	scope.createProxyFunction = function createProxyFunction(window, original, replacement){
-		const wrappedWindow = scope.getWrapped(window);
-		const handler = wrappedWindow.Object.create(wrappedWindow.Object);
-		handler.apply = scope.exportFunctionWithName(function(target, thisArgs, args){
-			// console.log(target, thisArgs, args);
-			return replacement.apply(thisArgs, args);
+		if (!changedToStrings.get(window)){
+			changedToStrings.set(window, true);
+			const functionPrototype = scope.getWrapped(window).Function.prototype;
+			const toString = functionPrototype.toString;
+			scope.changeProperty(window, "toString", {
+				object: functionPrototype,
+				name: "toString",
+				type: "value",
+				changed: scope.createProxyFunction(
+					window,
+					toString,
+					function(){
+						return proxies.get(this) || toString.call(this);
+					}
+				)
+			});
+		}
+		const handler = scope.getWrapped(window).Object.create(null);
+		handler.apply = scope.exportFunctionWithName(function(_target, thisArgs, args){
+			try {
+				return args.length?
+					replacement.call(thisArgs, ...args):
+					replacement.call(thisArgs);
+			}
+			catch (error){
+				return original.apply(thisArgs, args);
+			}
 		}, window, "");
-		return new wrappedWindow.Proxy(original, handler);
+		const proxy = new window.Proxy(original, handler);
+		proxies.set(proxy, original.toString());
+		return scope.getWrapped(proxy);
 	};
 	
 	const changedPropertiesByWindow = new WeakMap();