My guess would be that they made the figure in some tool like Adobe Illustrator, and while they were manipulating the labels into the right places, some numpty accidentally pressed the delete key with the wrong object selected. As Alex says, it looks like some amount of the outline is still visible, so possibly they even deleted the orange fill without deleting the outline. Or they were fiddling with the settings for the dark shading where the eclipse is visible, and accidentally had Britain selected at the time. 🙂
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