Creating a bar dataset with xAxis of type "type" can result in error "Cannot read property 'length' of undefined". Should add check for definition of data.labels before checking the length.
Adding empty labels[] to data avoids the error, but bars are drawn.
Adding the an empty Array literal for "labels" worked for me:
I think the label issue is fixed in master but still need #4673 for the {x, y}
bar data.
Fixed in master (https://jsfiddle.net/p8vLm0bj/19/)