Adding own package: Whole app broken in production

hopefully someone can help me. I try to create an internal package for RTCMutliConnection. I define my package.js like this:

    name: 'own:rtcmulti',
    version: '3.0.0'

Package.onUse(function (api) {

    api.addFiles('RTCMultiConnection.js', 'client');

In RTCMultiConnection.js, I’m adding the content of this file.

If I start my app in development mode, everythings works fine. But if I run it in production, my whole app breaks with the following console errors:

[Error] TypeError: undefined is not an object (evaluating 'window[e].prototype')
[Error] TypeError: undefined is not an object (evaluating 'Package["service-configuration"].ServiceConfiguration')

Any idea what’s going wrong?