cannot display exported calendar correctly #149

Hello, thanks for your great work.
I faced an issue when exporting mw cli. When I ran with mw markwhen.mw, it generated a timeline.html and can be viewed in Chrome, however, when I ran with mw markwhen.mw -o calendar or mw markwhen.mw -o resume, the output HTML file looks like a blank file with nothing opening with Chrome. The HTMLs have the file size, so they have the data, they just can't be displayed correctly.
How can I export the offline html calendar, I wanna insert it into the Hugo web page, thanks!
:)