Error thrown on transforming code containing sparse array

http://buble.surge.sh/#[%2C]

[,]

Transforming this throws an error:

TypeError: Cannot read property 'type' of null
    at ArrayExpression.initialise (/path/to/node_modules/buble/dist/buble.umd.js:251:19)

It's not just this weird minimal case that throws the error. As far as I can tell, any code containing a sparse array throws an error.