Strange E47 error (rear light)

Brand new Level 3, purchased about two months ago, 800 miles on it.

For some reason occasionally when I start riding, always when the battery is around 100% and I'm riding with the light on, I get an error telling me my rear light is malfunctioning. Both lights turn off and the display shows the red error screen. Unfortunately it also kills the pedal assist and I have to pull over, turn the bike off and back on and then everything is fine again.

It doesn't happen every time, I think so far it's happened maybe four times, and it's never happened twice on the same ride. It's not consistent enough to replicate.

Any ideas what might be going on?