When not in developer mode, the Log object does not get created because of an error, because there is no support for console.timeStamp in Edge/IE11. In developer mode it seems it just skips the error.
As a result, the call to Log.info throws an exception and halts execution in the init method in main.js which results in a black empty page.
commenting out the following line in logger.js fixed the problem.//timeStamp: Function.prototype.bind.call(console.timeStamp, console)
It seems Log.timeStamp is not used in MagicMirror and the modules that I use, so commenting it out worked for me. Better solution would be to have a polyfill I think.