can't read duckdb file

Hi, 

Thanks for QuackDB, great looking web-app, exactly what I was looking for.   

I dropped a .duckdb file into the sources pane, and it showed up there, but when I click to load it, I get an error saying 'unknown file type'.  It's a .duckdb file, which from the README I believe is supported?  Am I missing something obvious?

Thanks!