"Copy Image" doesn't work with Leaflet raster styles

[RossThorn]

When trying to get an image of a comparison involving a raster map, the "Copy Image" button doesn't work and instead shows a blank gray panel.

OpenStreetMap on the left vs Mapbox Outdoors on the right

Stamen Terrain on the left vs Mapbox Outdoors on the right

[aparlato]

Looking at this: I think this is just Leaflet styles specifically. When I use raster tiles in a mapbox gl style I see the expected result:

The code to screenshot probably references a canvas element that isn't present in our Leaflet rendering component.