fix Cannot access null value from map

lib/src/eval/runtime/ops/objects.dart

@@ -95,13 +95,23 @@ class InvokeDynamic implements EvcOp {
         runtime._prOffset = object.offset;
         return;
       }
-      final method = ((object as $Instance).$getProperty(runtime, _method)
-          as EvalFunction);
-      try {
-        runtime.returnValue = method.call(runtime, object, runtime.args.cast());
-      } catch (e) {
-        runtime.$throw(e);
+
+      if (object == null) {
+        object = $Null();
+      }
+
+      if (object is $Instance) {
+        final method = (object.$getProperty(runtime, _method) as EvalFunction);
+        try {
+          runtime.returnValue =
+              method.call(runtime, object, runtime.args.cast());
+        } catch (e) {
+          runtime.$throw(e);
+        }
+      } else {
+        runtime.returnValue = $null();
       }
+
       runtime.args = [];
       return;
     }
@@ -156,7 +166,14 @@ class CheckEq implements EvcOp {
         return;
       }
 
-      runtime.returnValue = v1 == v2;
+      if (v2 is $Value && v1 is! $Value) {
+        runtime.returnValue = v2.$value == v1;
+      } else if (v1 is $Value && v2 is! $Value) {
+        runtime.returnValue = v1.$value == v2;
+      } else {
+        runtime.returnValue = v1 == v2;
+      }
+
       return;
     }
   }
@@ -383,7 +400,7 @@ class IsType implements EvcOp {
 
   @override
   void run(Runtime runtime) {
-    final value = runtime.frame[_objectOffset] as $Value;
+    final value = (runtime.frame[_objectOffset] ?? $null()) as $Value;
     final type = value.$getRuntimeType(runtime);
     if (type < 0) {
       final result = type == _type;

lib/src/eval/runtime/ops/primitives.dart

@@ -332,7 +332,13 @@ class Unbox implements EvcOp {
 
   @override
   void run(Runtime runtime) {
-    runtime.frame[_reg] = (runtime.frame[_reg] as $Value).$value;
+    dynamic v = runtime.frame[_reg];
+
+    if (v is $Value) {
+      v = v.$value;
+    }
+
+    runtime.frame[_reg] = v;
   }
 
   @override

lib/src/eval/shared/stdlib/core.dart

@@ -80,6 +80,7 @@ class DartCorePlugin implements EvalPlugin {
     configureIdenticalForRuntime(runtime);
     $String.configureForRuntime(runtime);
     $List.configureForRuntime(runtime);
+    $Map.configureForRuntime(runtime);
     $MapEntry.configureForRuntime(runtime);
     $Iterable.configureForRuntime(runtime);
     $Duration.configureForRuntime(runtime);

lib/src/eval/shared/stdlib/core/base.dart

@@ -520,3 +520,71 @@ class $String implements $Instance {
   @override
   int get hashCode => $value.hashCode;
 }
+
+/// dart_eval [$Instance] representation of a [Null]
+class $Null implements $Instance {
+  $Null() : _superclass = $Object(_Null());
+
+  static const $declaration = BridgeClassDef(
+      BridgeClassType(BridgeTypeRef(CoreTypes.nullType), isAbstract: true),
+      constructors: {},
+      methods: {
+        // Other Null methods defined in builtins.dart
+      },
+      wrap: true);
+
+  final $Instance _superclass;
+
+  @override
+  $Value? $getProperty(Runtime runtime, String identifier) {
+    try {
+      return _superclass.$getProperty(runtime, identifier);
+    } catch (e) {
+      return $Function((
+        Runtime runtime,
+        $Value? target,
+        List<$Value?> args,
+      ) {
+        return $null();
+      });
+    }
+  }
+
+  @override
+  void $setProperty(Runtime runtime, String identifier, $Value value) {}
+
+  @override
+  _Null get $reified => $value;
+
+  @override
+  bool operator ==(Object other) {
+    return identical(this, other) ||
+        other is $Null &&
+            runtimeType == other.runtimeType &&
+            $value == other.$value;
+  }
+
+  @override
+  int get hashCode => $value.hashCode;
+
+  @override
+  String toString() {
+    return '\$${$value}';
+  }
+
+  @override
+  int $getRuntimeType(Runtime runtime) =>
+      runtime.lookupType(CoreTypes.nullType);
+
+  @override
+  get $value => _Null();
+}
+
+@pragma("vm:entry-point")
+class _Null extends Object {
+  String toString() => "null";
+
+  dynamic noSuchMethod(Invocation invocation) {
+    print("_Null.noSuchMethod(): $invocation");
+  }
+}

lib/src/eval/shared/stdlib/core/map.dart

@@ -5,10 +5,34 @@ class $Map<K, V> implements Map<K, V>, $Instance {
   /// Wrap a [Map] in a [$Map]
   $Map.wrap(this.$value);
 
+  static void configureForRuntime(Runtime runtime) {
+    return runtime.registerBridgeFunc(
+        'dart:core', 'Map.from', __$Map$from.call);
+  }
+
+  static const $type = BridgeTypeRef(CoreTypes.map);
+
   static const $declaration = BridgeClassDef(
-      BridgeClassType(BridgeTypeRef(CoreTypes.map),
-          generics: {'K': BridgeGenericParam(), 'V': BridgeGenericParam()}),
-      constructors: {},
+      BridgeClassType(
+        $type,
+        generics: {'K': BridgeGenericParam(), 'V': BridgeGenericParam()},
+      ),
+      constructors: {
+        'from': BridgeConstructorDef(
+          BridgeFunctionDef(
+            returns: BridgeTypeAnnotation($type),
+            params: [
+              BridgeParameter(
+                'other',
+                BridgeTypeAnnotation($type, nullable: false),
+                false,
+              )
+            ],
+            generics: {'K': BridgeGenericParam(), 'V': BridgeGenericParam()},
+          ),
+          isFactory: true,
+        ),
+      },
       methods: {
         '[]': BridgeMethodDef(
             BridgeFunctionDef(params: [
@@ -126,6 +150,14 @@ class $Map<K, V> implements Map<K, V>, $Instance {
     return _superclass.$setProperty(runtime, identifier, value);
   }
 
+  static const __$Map$from = $Function(_$Map$from);
+  static $Value? _$Map$from(
+      Runtime runtime, $Value? target, List<$Value?> args) {
+    final other = args[0]?.$value as Map;
+
+    return $Map.wrap(Map.from(other));
+  }
+
   static const $Function __indexGet = $Function(_indexGet);
 
   static $Value? _indexGet(

lib/src/eval/shared/stdlib/core/num.dart

@@ -46,6 +46,12 @@ class $num<T extends num> implements $Instance {
                     nullable: true),
                 params: []),
             isStatic: false),
+        'toDouble': BridgeMethodDef(
+            BridgeFunctionDef(
+                returns: BridgeTypeAnnotation(BridgeTypeRef(CoreTypes.double),
+                    nullable: true),
+                params: []),
+            isStatic: false),
         'ceil': BridgeMethodDef(
             BridgeFunctionDef(
                 returns: BridgeTypeAnnotation(BridgeTypeRef(CoreTypes.int),
@@ -129,6 +135,8 @@ class $num<T extends num> implements $Instance {
         return __compareTo;
       case 'toInt':
         return __toInt;
+      case 'toDouble':
+        return __toDouble;
       case 'ceil':
         return __ceil;
     }
@@ -276,6 +284,13 @@ class $num<T extends num> implements $Instance {
     return $int(_evalResult);
   }
 
+  static const $Function __toDouble = $Function(_toDouble);
+  static $Value? _toDouble(
+      Runtime runtime, $Value? target, List<$Value?> args) {
+    final _evalResult = (target!.$value as num).toDouble();
+    return $double(_evalResult);
+  }
+
   static const $Function __ceil = $Function(_ceil);
   static $Value? _ceil(Runtime runtime, $Value? target, List<$Value?> args) {
     final _evalResult = (target!.$value as num).ceil();