TypeError when running in Firefox

[r-martins]

Steps to reproduce:

1. Import JS
2. Run it with localIp option

Firefox 75 - MBP 15, 2018 - MacOs 10.15.4

TypeError: /([0-9]{1,3}(.[0-9]{1,3}){3}|[a-f0-9]{1,4}(:[a-f0-9]{1,4}){7})/.exec(...) is null imprint.js:594:81
onicecandidate https://cdn.jsdelivr.net/gh/mattbrailsford/imprintjs@master/dist/imprint.js:594
dispatchEvent resource://gre/modules/media/PeerConnection.jsm:818
dispatchEvent resource://gre/modules/media/PeerConnection.jsm:2007
onIceCandidate resource://gre/modules/media/PeerConnection.jsm:2055