There is a difference between List/Search and Get modules although they use the same method "GET".
List/Search modules return multiple bundles and should be Module type: Search.
Get modules return only 1 bundle (specified by the entered ID) and should be Module type: Action.
"Invalid module output. Expected Object, but found Array." error
If you happen to receive this error: Invalid module output. Expected Object, but found Array., it means that your module should be type Search. Type search expects an output type array, and unlike the type action supports pagination directive.
Data Error "Invalid module output."
Options > Edit Module
If you don't want to iterate the array returned from the API, you can wrap it in an object: