nullsafety

lib/src/engine.dart

@@ -15,20 +15,20 @@ typedef _JsHostPromiseRejectionHandler = void Function(dynamic reason);
 
 /// Quickjs engine for flutter.
 class FlutterQjs {
-  Pointer<JSRuntime> _rt;
-  Pointer<JSContext> _ctx;
+  Pointer<JSRuntime>? _rt;
+  Pointer<JSContext>? _ctx;
 
   /// Max stack size for quickjs.
-  final int stackSize;
+  final int? stackSize;
 
   /// Message Port for event loop. Close it to stop dispatching event loop.
   ReceivePort port = ReceivePort();
 
   /// Handler function to manage js module.
-  _JsModuleHandler moduleHandler;
+  final _JsModuleHandler? moduleHandler;
 
   /// Handler function to manage js module.
-  _JsHostPromiseRejectionHandler hostPromiseRejectionHandler;
+  final _JsHostPromiseRejectionHandler? hostPromiseRejectionHandler;
 
   FlutterQjs({
     this.moduleHandler,
@@ -38,7 +38,7 @@ class FlutterQjs {
 
   _ensureEngine() {
     if (_rt != null) return;
-    _rt = jsNewRuntime((ctx, type, ptr) {
+    final rt = jsNewRuntime((ctx, type, ptr) {
       try {
         switch (type) {
           case JSChannelType.METHON:
@@ -65,7 +65,7 @@ class FlutterQjs {
                 ));
           case JSChannelType.MODULE:
             if (moduleHandler == null) throw JSError('No ModuleHandler');
-            final ret = moduleHandler(
+            final ret = moduleHandler!(
               ptr.cast<Utf8>().toDartString(),
             ).toNativeUtf8();
             Future.microtask(() {
@@ -75,15 +75,14 @@ class FlutterQjs {
           case JSChannelType.PROMISE_TRACK:
             final err = _parseJSException(ctx, ptr);
             if (hostPromiseRejectionHandler != null) {
-              hostPromiseRejectionHandler(err);
+              hostPromiseRejectionHandler!(err);
             } else {
               print('unhandled promise rejection: $err');
             }
             return nullptr;
           case JSChannelType.FREE_OBJECT:
             final rt = ctx.cast<JSRuntime>();
-            _DartObject obj = _DartObject.fromAddress(rt, ptr.address);
-            obj?.free();
+            _DartObject.fromAddress(rt, ptr.address)?.free();
             return nullptr;
         }
         throw JSError('call channel with wrong type');
@@ -106,20 +105,21 @@ class FlutterQjs {
         return err;
       }
     }, port);
-    if (this.stackSize != null && this.stackSize > 0)
-      jsSetMaxStackSize(_rt, this.stackSize);
-    _ctx = jsNewContext(_rt);
+    final stackSize = this.stackSize ?? 0;
+    if (stackSize > 0) jsSetMaxStackSize(rt, stackSize);
+    _rt = rt;
+    _ctx = jsNewContext(rt);
   }
 
   /// Free Runtime and Context which can be recreate when evaluate again.
   close() {
-    if (_rt == null) return;
     final rt = _rt;
     final ctx = _ctx;
-    _executePendingJob();
     _rt = null;
     _ctx = null;
-    jsFreeContext(ctx);
+    if (ctx != null) jsFreeContext(ctx);
+    if (rt == null) return;
+    _executePendingJob();
     try {
       jsFreeRuntime(rt);
     } on String catch (e) {
@@ -128,11 +128,13 @@ class FlutterQjs {
   }
 
   void _executePendingJob() {
-    if (_rt == null) return;
+    final rt = _rt;
+    final ctx = _ctx;
+    if (rt == null || ctx == null) return;
     while (true) {
-      int err = jsExecutePendingJob(_rt);
+      int err = jsExecutePendingJob(rt);
       if (err <= 0) {
-        if (err < 0) print(_parseJSException(_ctx));
+        if (err < 0) print(_parseJSException(ctx));
         break;
       }
     }
@@ -146,20 +148,25 @@ class FlutterQjs {
   }
 
   /// Evaluate js script.
-  dynamic evaluate(String command, {String name, int evalFlags}) {
+  dynamic evaluate(
+    String command, {
+    String? name,
+    int? evalFlags,
+  }) {
     _ensureEngine();
+    final ctx = _ctx!;
     final jsval = jsEval(
-      _ctx,
+      ctx,
       command,
       name ?? '<eval>',
       evalFlags ?? JSEvalFlag.GLOBAL,
     );
     if (jsIsException(jsval) != 0) {
-      jsFreeValue(_ctx, jsval);
-      throw _parseJSException(_ctx);
+      jsFreeValue(ctx, jsval);
+      throw _parseJSException(ctx);
     }
-    final result = _jsToDart(_ctx, jsval);
-    jsFreeValue(_ctx, jsval);
+    final result = _jsToDart(ctx, jsval);
+    jsFreeValue(ctx, jsval);
     return result;
   }
 }

lib/src/ffi.dart

@@ -10,6 +10,16 @@ import 'dart:io';
 import 'dart:isolate';
 import 'package:ffi/ffi.dart';
 
+extension ListFirstWhere<T> on Iterable<T> {
+  T? firstWhereOrNull(bool Function(T) test) {
+    try {
+      return firstWhere(test);
+    } on StateError {
+      return null;
+    }
+  }
+}
+
 abstract class JSRef {
   int _refCount = 0;
   void dup() {
@@ -34,7 +44,7 @@ abstract class JSRef {
   static void _callRecursive(
     dynamic obj,
     void Function(JSRef) cb, [
-    Set cache,
+    Set? cache,
   ]) {
     if (obj == null) return;
     if (cache == null) cache = Set();
@@ -155,24 +165,26 @@ final Pointer<JSRuntime> Function(
     .asFunction();
 
 class _RuntimeOpaque {
-  _JSChannel _channel;
+  final _JSChannel _channel;
   List<JSRef> _ref = [];
-  ReceivePort _port;
-  int _dartObjectClassId;
-  get dartObjectClassId => _dartObjectClassId;
+  final ReceivePort _port;
+  int? _dartObjectClassId;
+  _RuntimeOpaque(this._channel, this._port);
+
+  int? get dartObjectClassId => _dartObjectClassId;
 
   void addRef(JSRef ref) => _ref.add(ref);
 
   bool removeRef(JSRef ref) => _ref.remove(ref);
 
-  JSRef getRef(bool Function(JSRef ref) test) {
-    return _ref.firstWhere(test, orElse: () => null);
+  JSRef? getRef(bool Function(JSRef ref) test) {
+    return _ref.firstWhereOrNull(test);
   }
 }
 
 final Map<Pointer<JSRuntime>, _RuntimeOpaque> runtimeOpaques = Map();
 
-Pointer<JSValue> channelDispacher(
+Pointer<JSValue>? channelDispacher(
   Pointer<JSContext> ctx,
   int type,
   Pointer<JSValue> argv,
@@ -188,9 +200,7 @@ Pointer<JSRuntime> jsNewRuntime(
   ReceivePort port,
 ) {
   final rt = _jsNewRuntime(Pointer.fromFunction(channelDispacher));
-  runtimeOpaques[rt] = _RuntimeOpaque()
-    .._channel = callback
-    .._port = port;
+  runtimeOpaques[rt] = _RuntimeOpaque(callback, port);
   return rt;
 }
 
@@ -222,21 +232,22 @@ void jsFreeRuntime(
   Pointer<JSRuntime> rt,
 ) {
   final referenceleak = <String>[];
-  while (true) {
-    final ref = runtimeOpaques[rt]
-        ?._ref
-        ?.firstWhere((ref) => ref is JSRefLeakable, orElse: () => null);
-    if (ref == null) break;
-    ref.destroy();
-    runtimeOpaques[rt]?._ref?.remove(ref);
-  }
-  while (0 < runtimeOpaques[rt]?._ref?.length ?? 0) {
-    final ref = runtimeOpaques[rt]?._ref?.first;
-    final objStrs = ref.toString().split('\n');
-    final objStr = objStrs.length > 0 ? objStrs[0] + " ..." : objStrs[0];
-    referenceleak.add(
-        "  ${identityHashCode(ref)}\t${ref._refCount + 1}\t${ref.runtimeType.toString()}\t$objStr");
-    ref.destroy();
+  final opaque = runtimeOpaques[rt];
+  if (opaque != null) {
+    while (true) {
+      final ref = opaque._ref.firstWhereOrNull((ref) => ref is JSRefLeakable);
+      if (ref == null) break;
+      ref.destroy();
+      runtimeOpaques[rt]?._ref.remove(ref);
+    }
+    while (opaque._ref.isNotEmpty) {
+      final ref = opaque._ref.first;
+      final objStrs = ref.toString().split('\n');
+      final objStr = objStrs.length > 0 ? objStrs[0] + " ..." : objStrs[0];
+      referenceleak.add(
+          "  ${identityHashCode(ref)}\t${ref._refCount + 1}\t${ref.runtimeType.toString()}\t$objStr");
+      ref.destroy();
+    }
   }
   _jsFreeRuntime(rt);
   if (referenceleak.length > 0) {
@@ -335,7 +346,7 @@ Pointer<JSValue> jsEval(
   );
   malloc.free(utf8input);
   malloc.free(utf8filename);
-  runtimeOpaques[jsGetRuntime(ctx)]._port.sendPort.send(#eval);
+  runtimeOpaques[jsGetRuntime(ctx)]?._port.sendPort.send(#eval);
   return val;
 }
 
@@ -915,14 +926,11 @@ Pointer<JSValue> jsCall(
     setJSValueList(jsArgs, i, jsArg);
   }
   final func1 = jsDupValue(ctx, funcObj);
-  final _thisObj = thisObj ?? jsUNDEFINED();
+  final _thisObj = thisObj;
   final jsRet = _jsCall(ctx, funcObj, _thisObj, argv.length, jsArgs);
-  if (thisObj == null) {
-    jsFreeValue(ctx, _thisObj);
-  }
   jsFreeValue(ctx, func1);
   malloc.free(jsArgs);
-  runtimeOpaques[jsGetRuntime(ctx)]._port.sendPort.send(#call);
+  runtimeOpaques[jsGetRuntime(ctx)]?._port.sendPort.send(#call);
   return jsRet;
 }
 

lib/src/isolate.dart

@@ -17,7 +17,7 @@ abstract class _IsolateEncodable {
   Map _encode();
 }
 
-dynamic _encodeData(dynamic data, {Map<dynamic, dynamic> cache}) {
+dynamic _encodeData(dynamic data, {Map<dynamic, dynamic>? cache}) {
   if (cache == null) cache = Map();
   if (cache.containsKey(data)) return cache[data];
   if (data is _IsolateEncodable) return data._encode();
@@ -58,7 +58,7 @@ dynamic _encodeData(dynamic data, {Map<dynamic, dynamic> cache}) {
   return data;
 }
 
-dynamic _decodeData(dynamic data, {Map<dynamic, dynamic> cache}) {
+dynamic _decodeData(dynamic data, {Map<dynamic, dynamic>? cache}) {
   if (cache == null) cache = Map();
   if (cache.containsKey(data)) return cache[data];
   if (data is List) {
@@ -132,7 +132,7 @@ void _runJsIsolate(Map spawnMessage) async {
   );
   port.listen((msg) async {
     var data;
-    SendPort msgPort = msg[#port];
+    SendPort? msgPort = msg[#port];
     try {
       switch (msg[#type]) {
         case #evaluate:
@@ -164,16 +164,16 @@ void _runJsIsolate(Map spawnMessage) async {
 typedef _JsAsyncModuleHandler = Future<String> Function(String name);
 
 class IsolateQjs {
-  Future<SendPort> _sendPort;
+  Future<SendPort>? _sendPort;
 
   /// Max stack size for quickjs.
-  final int stackSize;
+  final int? stackSize;
 
   /// Asynchronously handler to manage js module.
-  _JsAsyncModuleHandler moduleHandler;
+  final _JsAsyncModuleHandler? moduleHandler;
 
   /// Handler function to manage js module.
-  _JsHostPromiseRejectionHandler hostPromiseRejectionHandler;
+  final _JsHostPromiseRejectionHandler? hostPromiseRejectionHandler;
 
   /// Quickjs engine runing on isolate thread.
   ///
@@ -207,7 +207,7 @@ class IsolateQjs {
           try {
             final err = _decodeData(msg[#reason]);
             if (hostPromiseRejectionHandler != null) {
-              hostPromiseRejectionHandler(err);
+              hostPromiseRejectionHandler!(err);
             } else {
               print('unhandled promise rejection: $err');
             }
@@ -218,7 +218,7 @@ class IsolateQjs {
         case #module:
           final ptr = Pointer<Pointer>.fromAddress(msg[#ptr]);
           try {
-            ptr.value = (await moduleHandler(msg[#name])).toNativeUtf8();
+            ptr.value = (await moduleHandler!(msg[#name])).toNativeUtf8();
           } catch (e) {
             ptr.value = Pointer.fromAddress(-1);
           }
@@ -234,8 +234,10 @@ class IsolateQjs {
 
   /// Free Runtime and close isolate thread that can be recreate when evaluate again.
   close() {
-    if (_sendPort == null) return;
-    final ret = _sendPort.then((sendPort) async {
+    final sendPort = _sendPort;
+    _sendPort = null;
+    if (sendPort == null) return;
+    final ret = sendPort.then((sendPort) async {
       final closePort = ReceivePort();
       sendPort.send({
         #type: #close,
@@ -247,15 +249,18 @@ class IsolateQjs {
         throw _decodeData(result[#error]);
       return _decodeData(result);
     });
-    _sendPort = null;
     return ret;
   }
 
   /// Evaluate js script.
-  Future<dynamic> evaluate(String command, {String name, int evalFlags}) async {
+  Future<dynamic> evaluate(
+    String command, {
+    String? name,
+    int? evalFlags,
+  }) async {
     _ensureEngine();
     final evaluatePort = ReceivePort();
-    final sendPort = await _sendPort;
+    final sendPort = await _sendPort!;
     sendPort.send({
       #type: #evaluate,
       #command: command,

lib/src/object.dart

@@ -48,17 +48,18 @@ class _DartFunction extends JSInvokable {
 /// implement this to capture js object release.
 
 class _DartObject extends JSRef implements JSRefLeakable {
-  Object _obj;
-  Pointer<JSContext> _ctx;
-  _DartObject(this._ctx, this._obj) {
-    if (_obj is JSRef) {
-      (_obj as JSRef).dup();
-    }
-    runtimeOpaques[jsGetRuntime(_ctx)]?.addRef(this);
+  Object? _obj;
+  Pointer<JSContext>? _ctx;
+  _DartObject(Pointer<JSContext> ctx, dynamic obj) {
+    _ctx = ctx;
+    _obj = obj;
+    if (obj is JSRef) obj.dup();
+    runtimeOpaques[jsGetRuntime(ctx)]?.addRef(this);
   }
 
-  static _DartObject fromAddress(Pointer<JSRuntime> rt, int val) {
-    return runtimeOpaques[rt]?.getRef((e) => identityHashCode(e) == val);
+  static _DartObject? fromAddress(Pointer<JSRuntime> rt, int val) {
+    return runtimeOpaques[rt]?.getRef((e) => identityHashCode(e) == val)
+        as _DartObject?;
   }
 
   @override
@@ -69,20 +70,20 @@ class _DartObject extends JSRef implements JSRefLeakable {
 
   @override
   void destroy() {
-    if (_ctx == null) return;
-    runtimeOpaques[jsGetRuntime(_ctx)]?.removeRef(this);
+    final ctx = _ctx;
+    final obj = _obj;
     _ctx = null;
-    if (_obj is JSRef) {
-      (_obj as JSRef).free();
-    }
     _obj = null;
+    if (ctx == null) return;
+    runtimeOpaques[jsGetRuntime(ctx)]?.removeRef(this);
+    if (obj is JSRef) obj.free();
   }
 }
 
 /// JS Error wrapper
 class JSError extends _IsolateEncodable {
-  String message;
-  String stack;
+  late String message;
+  late String stack;
   JSError(message, [stack]) {
     if (message is JSError) {
       this.message = message.message;
@@ -95,10 +96,10 @@ class JSError extends _IsolateEncodable {
 
   @override
   String toString() {
-    return stack == null ? message.toString() : "$message\n$stack";
+    return stack.isEmpty ? message.toString() : "$message\n$stack";
   }
 
-  static JSError _decode(Map obj) {
+  static JSError? _decode(Map obj) {
     if (obj.containsKey(#jsError))
       return JSError(obj[#jsError], obj[#jsErrorStack]);
     return null;
@@ -116,30 +117,33 @@ class JSError extends _IsolateEncodable {
 /// JS Object reference
 /// call [release] to release js object.
 class _JSObject extends JSRef {
-  Pointer<JSValue> _val;
-  Pointer<JSContext> _ctx;
+  Pointer<JSValue>? _val;
+  Pointer<JSContext>? _ctx;
 
   /// Create
-  _JSObject(this._ctx, Pointer<JSValue> _val) {
-    final rt = jsGetRuntime(_ctx);
-    this._val = jsDupValue(_ctx, _val);
+  _JSObject(Pointer<JSContext> ctx, Pointer<JSValue> val) {
+    this._ctx = ctx;
+    final rt = jsGetRuntime(ctx);
+    this._val = jsDupValue(ctx, val);
     runtimeOpaques[rt]?.addRef(this);
   }
 
   @override
   void destroy() {
-    if (_val == null) return;
-    final rt = jsGetRuntime(_ctx);
-    runtimeOpaques[rt]?.removeRef(this);
-    jsFreeValue(_ctx, _val);
+    final ctx = _ctx;
+    final val = _val;
     _val = null;
     _ctx = null;
+    if (ctx == null || val == null) return;
+    final rt = jsGetRuntime(ctx);
+    runtimeOpaques[rt]?.removeRef(this);
+    jsFreeValue(ctx, val);
   }
 
   @override
   String toString() {
-    if (_val == null) return "JSObject(released)";
-    return jsToCString(_ctx, _val);
+    if (_ctx == null || _val == null) return "JSObject(released)";
+    return jsToCString(_ctx!, _val!);
   }
 }
 
@@ -150,29 +154,32 @@ class _JSFunction extends _JSObject implements JSInvokable, _IsolateEncodable {
   @override
   invoke(List<dynamic> arguments, [dynamic thisVal]) {
     final jsRet = _invoke(arguments, thisVal);
-    if (jsRet == null) return;
+    final ctx = _ctx!;
     bool isException = jsIsException(jsRet) != 0;
     if (isException) {
-      jsFreeValue(_ctx, jsRet);
-      throw _parseJSException(_ctx);
+      jsFreeValue(ctx, jsRet);
+      throw _parseJSException(ctx);
     }
-    final ret = _jsToDart(_ctx, jsRet);
-    jsFreeValue(_ctx, jsRet);
+    final ret = _jsToDart(ctx, jsRet);
+    jsFreeValue(ctx, jsRet);
     return ret;
   }
 
   Pointer<JSValue> _invoke(List<dynamic> arguments, [dynamic thisVal]) {
-    if (_val == null) throw JSError("InternalError: JSValue released");
+    final ctx = _ctx;
+    final val = _val;
+    if (ctx == null || val == null)
+      throw JSError("InternalError: JSValue released");
     final args = arguments
         .map(
-          (e) => _dartToJs(_ctx, e),
+          (e) => _dartToJs(ctx, e),
         )
         .toList();
-    final jsThis = _dartToJs(_ctx, thisVal);
-    final jsRet = jsCall(_ctx, _val, jsThis, args);
-    jsFreeValue(_ctx, jsThis);
+    final jsThis = _dartToJs(ctx, thisVal);
+    final jsRet = jsCall(ctx, val, jsThis, args);
+    jsFreeValue(ctx, jsThis);
     for (final jsArg in args) {
-      jsFreeValue(_ctx, jsArg);
+      jsFreeValue(ctx, jsArg);
     }
     return jsRet;
   }
@@ -185,9 +192,9 @@ class _JSFunction extends _JSObject implements JSInvokable, _IsolateEncodable {
 
 /// Dart function wrapper for isolate
 class IsolateFunction extends JSInvokable implements _IsolateEncodable {
-  int _isolateId;
-  SendPort _port;
-  JSInvokable _invokable;
+  int? _isolateId;
+  SendPort? _port;
+  JSInvokable? _invokable;
   IsolateFunction._fromId(this._isolateId, this._port);
 
   IsolateFunction._new(this._invokable) {
@@ -195,18 +202,17 @@ class IsolateFunction extends JSInvokable implements _IsolateEncodable {
   }
   IsolateFunction(Function func) : this._new(_DartFunction(func));
 
-  static ReceivePort _invokeHandler;
+  static ReceivePort? _invokeHandler;
   static Set<IsolateFunction> _handlers = Set();
 
   static get _handlePort {
     if (_invokeHandler == null) {
       _invokeHandler = ReceivePort();
-      _invokeHandler.listen((msg) async {
+      _invokeHandler!.listen((msg) async {
         final msgPort = msg[#port];
         try {
-          final handler = _handlers.firstWhere(
+          final handler = _handlers.firstWhereOrNull(
             (v) => identityHashCode(v) == msg[#handler],
-            orElse: () => null,
           );
           if (handler == null) throw JSError('handler released');
           final ret = _encodeData(await handler._handle(msg[#msg]));
@@ -220,13 +226,14 @@ class IsolateFunction extends JSInvokable implements _IsolateEncodable {
         }
       });
     }
-    return _invokeHandler.sendPort;
+    return _invokeHandler!.sendPort;
   }
 
   _send(msg) async {
-    if (_port == null) return _handle(msg);
+    final port = _port;
+    if (port == null) return _handle(msg);
     final evaluatePort = ReceivePort();
-    _port.send({
+    port.send({
       #handler: _isolateId,
       #msg: msg,
       #port: evaluatePort.sendPort,
@@ -240,6 +247,7 @@ class IsolateFunction extends JSInvokable implements _IsolateEncodable {
   _destroy() {
     _handlers.remove(this);
     _invokable?.free();
+    _invokable = null;
   }
 
   _handle(msg) async {
@@ -257,7 +265,7 @@ class IsolateFunction extends JSInvokable implements _IsolateEncodable {
     }
     final List args = _decodeData(msg[#args]);
     final thisVal = _decodeData(msg[#thisVal]);
-    return _invokable.invoke(args, thisVal);
+    return _invokable?.invoke(args, thisVal);
   }
 
   @override
@@ -270,7 +278,7 @@ class IsolateFunction extends JSInvokable implements _IsolateEncodable {
     });
   }
 
-  static IsolateFunction _decode(Map obj) {
+  static IsolateFunction? _decode(Map obj) {
     if (obj.containsKey(#jsFunctionPort))
       return IsolateFunction._fromId(
         obj[#jsFunctionId],

lib/src/wrapper.dart

@@ -7,7 +7,7 @@
  */
 part of '../flutter_qjs.dart';
 
-dynamic _parseJSException(Pointer<JSContext> ctx, [Pointer<JSValue> perr]) {
+dynamic _parseJSException(Pointer<JSContext> ctx, [Pointer<JSValue>? perr]) {
   final e = perr ?? jsGetException(ctx);
   var err;
   try {
@@ -24,7 +24,7 @@ void _definePropertyValue(
   Pointer<JSValue> obj,
   dynamic key,
   dynamic val, {
-  Map<dynamic, Pointer<JSValue>> cache,
+  Map<dynamic, Pointer<JSValue>>? cache,
 }) {
   final jsAtomVal = _dartToJs(ctx, key, cache: cache);
   final jsAtom = jsValueToAtom(ctx, jsAtomVal);
@@ -43,7 +43,7 @@ Pointer<JSValue> _jsGetPropertyValue(
   Pointer<JSContext> ctx,
   Pointer<JSValue> obj,
   dynamic key, {
-  Map<dynamic, dynamic> cache,
+  Map<dynamic, Pointer<JSValue>>? cache,
 }) {
   final jsAtomVal = _dartToJs(ctx, key, cache: cache);
   final jsAtom = jsValueToAtom(ctx, jsAtomVal);
@@ -54,7 +54,7 @@ Pointer<JSValue> _jsGetPropertyValue(
 }
 
 Pointer<JSValue> _dartToJs(Pointer<JSContext> ctx, dynamic val,
-    {Map<dynamic, Pointer<JSValue>> cache}) {
+    {Map<dynamic, Pointer<JSValue>>? cache}) {
   if (val == null) return jsUNDEFINED();
   if (val is Error) return _dartToJs(ctx, JSError(val, val.stackTrace));
   if (val is Exception) return _dartToJs(ctx, JSError(val));
@@ -65,7 +65,7 @@ Pointer<JSValue> _dartToJs(Pointer<JSContext> ctx, dynamic val,
     _definePropertyValue(ctx, ret, "stack", val.stack);
     return ret;
   }
-  if (val is _JSObject) return jsDupValue(ctx, val._val);
+  if (val is _JSObject) return jsDupValue(ctx, val._val!);
   if (val is Future) {
     final resolvingFunc = malloc<Uint8>(sizeOfJSValue * 2).cast<JSValue>();
     final resolvingFunc2 =
@@ -104,7 +104,7 @@ Pointer<JSValue> _dartToJs(Pointer<JSContext> ctx, dynamic val,
     return ret;
   }
   if (cache.containsKey(val)) {
-    return jsDupValue(ctx, cache[val]);
+    return jsDupValue(ctx, cache[val]!);
   }
   if (val is List) {
     final ret = jsNewArray(ctx);
@@ -141,7 +141,7 @@ Pointer<JSValue> _dartToJs(Pointer<JSContext> ctx, dynamic val,
 }
 
 dynamic _jsToDart(Pointer<JSContext> ctx, Pointer<JSValue> val,
-    {Map<int, dynamic> cache}) {
+    {Map<int, dynamic>? cache}) {
   if (cache == null) cache = Map();
   final tag = jsValueGetTag(val);
   if (jsTagIsFloat64(tag) != 0) {
@@ -156,8 +156,8 @@ dynamic _jsToDart(Pointer<JSContext> ctx, Pointer<JSValue> val,
       return jsToCString(ctx, val);
     case JSTag.OBJECT:
       final rt = jsGetRuntime(ctx);
-      final dartObjectClassId = runtimeOpaques[rt].dartObjectClassId;
-      if (dartObjectClassId != 0) {
+      final dartObjectClassId = runtimeOpaques[rt]?.dartObjectClassId;
+      if (dartObjectClassId != null) {
         final dartObject = _DartObject.fromAddress(
             rt, jsGetObjectOpaque(val, dartObjectClassId));
         if (dartObject != null) return dartObject._obj;
@@ -243,7 +243,6 @@ dynamic _jsToDart(Pointer<JSContext> ctx, Pointer<JSValue> val,
         malloc.free(ptab);
         return ret;
       }
-      break;
     default:
   }
   return null;