Update

Kha/Tools/windows_x64/std/neko/Boot.hx

@@ -48,7 +48,11 @@ class Boot {
 			i += 1;
 		}
 		e.__string = old;
+		#if haxe_next
+		return NativeString.ofString(s + untyped ")".__s);
+		#else
 		return s + untyped ")".__s;
+		#end
 	}
 
 	private static function __interfLoop(cc:Dynamic, cl:Dynamic) {
@@ -108,15 +112,14 @@ class Boot {
 		}
 	}
 
-	private static function __tagserialize(o:Dynamic)
-		untyped {
-			var n = o.__enum__.__ename__;
-			var x = __dollar__amake(n.length + 1);
-			for (i in 0...n.length)
-				x[i] = n[i].__s;
-			x[n.length] = o.tag;
-			return x;
-		}
+	private static function __tagserialize(o:Dynamic) untyped {
+		var n = o.__enum__.__ename__;
+		var x = __dollar__amake(n.length + 1);
+		for (i in 0...n.length)
+			x[i] = n[i].__s;
+		x[n.length] = o.tag;
+		return x;
+	}
 
 	private static function __unserialize(v:Dynamic) {
 		untyped {
@@ -125,7 +128,7 @@ class Boot {
 			for (i in 0...__dollar__asize(v))
 				if (__dollar__typeof(v[i]) != __dollar__tstring)
 					throw "Invalid serialized class data";
-			var cl = neko.Boot.__classes;
+			var cl:Dynamic = neko.Boot.__classes;
 			for (i in 0...__dollar__asize(v)) {
 				cl = __dollar__objget(cl, __dollar__hash(v[i]));
 				if (cl == null)

Kha/Tools/windows_x64/std/neko/_std/Sys.hx

@@ -69,7 +69,7 @@ import haxe.SysTools;
 		return new String(v);
 	}
 
-	public static function putEnv( s : String, v : String ) : Void {
+	public static function putEnv( s : String, v : Null<String> ) : Void {
 		untyped put_env(s.__s,if( v == null ) null else v.__s);
 	}
 

Kha/Tools/windows_x64/std/neko/_std/haxe/Exception.hx

@@ -18,7 +18,10 @@ class Exception {
 		if(Std.isOfType(value, Exception)) {
 			return value;
 		} else {
-			return new ValueException(value, null, value);
+			var e = new ValueException(value, null, value);
+			// Undo automatic __shiftStack()
+			e.__unshiftStack();
+			return e;
 		}
 	}
 
@@ -63,6 +66,12 @@ class Exception {
 		__skipStack++;
 	}
 
+	@:noCompletion
+	@:ifFeature("haxe.Exception.get_stack")
+	inline function __unshiftStack():Void {
+		__skipStack--;
+	}
+
 	function get_message():String {
 		return __exceptionMessage;
 	}

Kha/Tools/windows_x64/std/neko/_std/haxe/ds/IntMap.hx

@@ -74,7 +74,7 @@ package haxe.ds;
 
 	public function toString():String {
 		var s = new StringBuf();
-		s.add("{");
+		s.add("[");
 		var it = keys();
 		for (i in it) {
 			s.add(i);
@@ -83,7 +83,7 @@ package haxe.ds;
 			if (it.hasNext())
 				s.add(", ");
 		}
-		s.add("}");
+		s.add("]");
 		return s.toString();
 	}
 

Kha/Tools/windows_x64/std/neko/_std/haxe/ds/ObjectMap.hx

@@ -94,7 +94,7 @@ class ObjectMap<K:{}, V> implements haxe.Constraints.IMap<K, V> {
 
 	public function toString():String {
 		var s = new StringBuf();
-		s.add("{");
+		s.add("[");
 		var it = keys();
 		for (i in it) {
 			s.add(Std.string(i));
@@ -103,7 +103,7 @@ class ObjectMap<K:{}, V> implements haxe.Constraints.IMap<K, V> {
 			if (it.hasNext())
 				s.add(", ");
 		}
-		s.add("}");
+		s.add("]");
 		return s.toString();
 	}
 

Kha/Tools/windows_x64/std/neko/_std/haxe/ds/StringMap.hx

@@ -74,7 +74,7 @@ package haxe.ds;
 
 	public function toString():String {
 		var s = new StringBuf();
-		s.add("{");
+		s.add("[");
 		var it = keys();
 		for (i in it) {
 			s.add(i);
@@ -83,7 +83,7 @@ package haxe.ds;
 			if (it.hasNext())
 				s.add(", ");
 		}
-		s.add("}");
+		s.add("]");
 		return s.toString();
 	}