Search ahead API returning "error": "Parameter 'collection': invalid collection type: []"

I run the following GET request in my code to test the search ahead API:

`http://www.mapquestapi.com/search/v3/prediction?key=KEY&limit=5&collecti...${event.target.value}`

It worked fine up until this morning, when I started to get the following error:

"error": "Parameter 'collection': invalid collection type: []"

Is this a problem on my end or from the API?