SpriteKit game on macOS: "Execution of the command buffer was aborted due to an error during execution."

Question

I'm running into a strange intermittent bug on a game I'm developing for iOS and macOS using SpriteKit. After launching on the Mac and waiting some random amount of time, the game window starts flickering (see below) and I start getting the following console errors:

2016-10-20 12:52:43.000352 RobotGame-macOS[27086:790757] Execution of the command buffer was aborted due to an error during execution. <private>
2016-10-20 12:52:43.000432 RobotGame-macOS[27086:790757] Execution of the command buffer was aborted due to an error during execution. <private>
2016-10-20 12:52:57.139097 RobotGame-macOS[27086:790803] Execution of the command buffer was aborted due to an error during execution. <private>
2016-10-20 12:52:57.139173 RobotGame-macOS[27086:790803] Execution of the command buffer was aborted due to an error during execution. <private>

I've currently designed all the graphics using basic SpriteKit SKNodes with no other custom shaders or any other advanced Metal stuff.

So what is causing this? I don't know where to begin with debugging it.