`geom_pointpath` throws error when group only has 1 member

[teunbrand]

library(ggplot2)
library(ggh4x)

df <- data.frame(x = 1, y = 1)

ggplot(df, aes(x, y)) +
  geom_pointpath()
#> Error in unit(data$x, "npc"): 'x' and 'units' must have length > 0

^{Created on 2021-06-10 by the reprex package (v1.0.0)}

[teunbrand]

This now works:

library(ggplot2)
library(ggh4x)

df <- data.frame(x = 1, y = 1)

ggplot(df, aes(x, y)) +
  geom_pointpath()

^{Created on 2021-06-21 by the reprex package (v1.0.0)}