players-inside convenience function broken

[brunchboy]

Describe the bug
At some point in reorganizing the show namespace to add support for phrase cues, the players-inside convenience value became disconnected with the implementation that it tried to resolve reflectively, causing a cryptic crash when it was used.

To Reproduce
Create a cue expression that tries to use players-inside.

Expected behavior
It should return a set of the player numbers currently positioned inside the cue.