Before you consider my question as duplicate, I already tried everything answered in other questions and no success. Let me explain my problem:

I have an Angular 2 App and an Express API sharing a private package written in Typescript that contains classes for my domain. All of them are using Typescript 2.2.2.

In the priavte package there is a class that extends another class in another file and the project compiles. The problem happens when I try to use the package in my Angular app: everything breaks and the console shows TypeError: Object prototype may only be an Object or null: undefined.

That only happens if the child class is present in the package, otherwise everything works fine.

Ex:

// child/child.ts

import { Parent } from '../parent/parent';

export class Child extends Parent { }

// parent/parent.ts
export class Parent {
    foo: string;
}

// bar/bar.ts
import { Child } from '../child/child';

export class Bar {
    child: Child;
}

In the private package I'm using Gulp to compile Typescript to Javascript and generate the declarations file.

Here is the .tsconfig file:

{
    "compilerOptions": {
        "target": "es5",
        "noImplicitAny": true,
        "preserveConstEnums": true,
        "sourceMap": true,
        "experimentalDecorators": true,
        "typeRoots": ["../node_modules/@types"],
        "declaration": true,
        "removeComments": false
    },
    "include": [
        "**/**.ts"
    ],
    "exclude": [
        "node_modules"
    ]
}

Here is the .gulpfile.js:

var gulp = require('gulp');
var ts = require('gulp-typescript');
var merge = require('merge2');
var tsConfig = ts.createProject('tsconfig.json', { declaration: true });

gulp.task("release", [], () => {
    var tsResult = gulp.src('src/**/**.ts')
        .pipe(tsConfig());

    return merge([
        tsResult.dts.pipe(gulp.dest('release/definitions')),
        tsResult.js.pipe(gulp.dest('release/js'))
    ]);
});

My files structure:

+ root
|
+--+ bar
|  |
|  +-- bar.ts
|
+--+ child
|  |
|  +-- child.ts
|
+--+ parent
   |
   +-- parent.ts

I've read that it could be a problem with sorting the classes names when compiling, because Parent has to be compiled before Child. The solution would be writing the directive /// <reference path="parent/parent"> in my child class, but when I try to compile it fails and says the reference directive doesn't exist. If I write references instead of reference it compiles, but the resulting js files are the same, except by that extra line, and don't work.