guide_coloursteps(show.limits = T) produces strange lower limit

[davidhodge931]

library(tidyverse)

ggplot(mpg, aes(displ, hwy, colour = hwy)) +
  geom_point() +
  guides(colour = guide_coloursteps(show.limits = T))

^{Created on 2024-04-29 with reprex v2.1.0}

[teunbrand]

The reason for this is that 10 is an out-of-bounds break that for some reason doesn't get censored.
The scale then assigns a colour for 11 (because (10 + 12) / 2 = 11), which is under the lower limit of 12, so it gets na.value.
Out-of-bounds breaks should probably be removed.