Calendar with events that have "null" location variables raise exceptions

[vilhelmprytz]

I have a .ics file that has events that do not have a location value, they are null. These .ics files are not renderable with this. See the error message.

It seems like Chrome is complaining about this line, line 126 in embed.js.

if (event.location.startsWith('http')) {

I have already fixed this, see linked PR (#3).