I was testing my submission code, starting with "playing now".

I had assumed that submitting a payload with 0 listens in that case would either:

1. Give an error
2. Clear the "playing now" info (for the case where the user presses pause/stop in their player)

It looks like neither is the case. Such a submission is simply accepted, but a previously-submitted "playing now" keeps being shown on the user's profile page (presumedly until it times out).

Where it does differ is that a normal successful submit (containing a single listen) returns '

', while a submit with 0 listens returns "success".

I would not expect a difference in return between valid submissions of the same type; either a single/playing_now with 0 listens should error out (the way one with more than one would), or it should have the same result as a single-listen case.