Bugsnag: Cannot set properties of undefined (setting 'apiKey')

[telmaantunes]

In a website using SystemJS, the bugsnag initialization fails with the following message

Bugsnag TypeError: window.require is not a function

SystemJS does not define window.require therefore I've added require to my project and now the integration initializes but gives me the following error:

[Bugsnag] Invalid API key 'undefined'
Uncaught TypeError: Cannot set properties of undefined (setting 'apiKey')

PS: I've obviously confirmed that the Bugsnag destination on segment has its key there.