Affects Version/s: Minecraft 1.12, Minecraft 1.12.2
Fix Version/s: Minecraft 17w45a
If a selector that only has the potential to select one entity (@p, @s, @r, @e[c=1], @a[c=1]) has 4 minus signs, it attempts and fails to parse as a UUID.
Which results in:
Whereas the expected normal error message (for just not finding the entity) would be: