When indexing an array field for lat/long:

for a collection, it will error out if not all objects in the collection have the location array populated. So, if you have 10 objects and 1 does not have a lat/long, it will error out.

Here is the console output:

> db.hotels.ensureIndex(

)
geo field[location] has to be an Object or Array

It seems like this should not error out, but rather skip over the ones that are not populated.