Gjs doesn't seem to execute Vala constructors. test.js should print 5 but instead it prints 0.

build.sh

#!/bin/sh

valac gjs_constructor_test.vala -X -fPIC -X -shared -o gjs_constructor_test.so --library=GjsConstructorTest --gir GjsConstructorTest-0.1.gir
g-ir-compiler --shared-library=gjs_constructor_test.so --output=GjsConstructorTest-0.1.typelib GjsConstructorTest-0.1.gir
cp gjs_constructor_test.so /usr/lib/
cp GjsConstructorTest-0.1.typelib /usr/lib/girepository-1.0/

gjs_constructor_test.vala

namespace GjsConstructorTest {
    public class TestClass : GLib.Object
    {
        private int field;

        public TestClass () {
            this.field = 5;
        }

        public int getField () {
            return this.field;
        }
    }
}

test.js

#!/bin/gjs

const TestClass = imports.gi.GjsConstructorTest.TestClass
let test = new TestClass()
print(test.getField())