Import a ES6 module in Angular

I’m trying to use H5 to convert C# code into JS and then use the result in an Angular project, but I’m having trouble importing the generated JS module.

I wrote a simple C# class like this:

namespace TW3.Shared {
    public class Class1 {
        public int Sum(int x, int y) {
            return x + y;
        }
    }
}

…and using the following h5.json configuration file:

{
    "module": {
        "type": "ES6",
        "name": "XXX"
    },
    "generateTypeScript": true
}

…I got these 2 files:

// SharedJS.js

/**
 * @compiler H5 24.2.45744+d8342060ba1fec4b36b7d0c2865c74ad945e2889
 */
H5.assemblyVersion("SharedJS","1.0.0.0");
H5.assembly("SharedJS", function ($asm, globals) {
    "use strict";

    (function () {
        var XXX = { };
        H5.define("TW3.Shared.Class1", {
            $metadata : function () { return {"att":1048577,"a":2,"m":[{"a":2,"isSynthetic":true,"n":".ctor","t":1,"sn":"ctor"},{"a":2,"n":"Sum","t":8,"pi":[{"n":"x","pt":System.Int32,"ps":0},{"n":"y","pt":System.Int32,"ps":1}],"sn":"Sum","rt":System.Int32,"p":[System.Int32,System.Int32],"box":function ($v) { return H5.box($v, System.Int32);}}]}; },
            $scope: XXX,
            $module: "XXX",
            methods: {
                Sum: function (x, y) {
                    return ((x + y) | 0);
                }
            }
        });
        export {XXX};
    }) ();

});

// SharedJS.d.ts

namespace TW3.Shared {
    interface Class1 {
        Sum(x: number, y: number): number;
    }
    interface Class1Func extends Function {
        prototype: Class1;
        new (): Class1;
    }
    var Class1: Class1Func;
}

So, what do I need to do in order to call Class1.Sum() inside Angular?

I tried adding the generated .js and .ts files to angular.json:

"scripts": [
  "src/assets/js/SharedJS/h5.js",
  "src/assets/js/SharedJS/h5.meta.js",
  "src/assets/js/SharedJS/SharedJS.js",
  "src/assets/js/SharedJS/SharedJS.meta.js",
  "src/assets/js/SharedJS/SharedJS.d.ts"
]

but if I do that, then I get an error when I try to build the angular project:

X [ERROR] Unexpected "export"

    angular:script/global:scripts.js:51675:8:
      51675 │         export {XXX};
            ╵         ~~~~~~