Error with `hjust = "right"` when used together with `size` aesthetic

[aphalo]

@teunbrand @thomasp85 This bug breaks unit tests in 'ggpp', but I can reproduce the bug using 'ggplot2' on its own.

The first example below used to work without error in 'ggplot2' (==3.4.4.9000) until quite recently (or at least 'ggpp' tests worked), but is now broken. Based on the second and third examples below, it seems that the combined use of the size aesthetic and hjust = "right" is what triggers the error.

With the current version here at GitHub I see:

library(ggplot2)
packageVersion("ggplot2")
#> [1] '3.4.4.9000'
packageDate("ggplot2")
#> [1] "2023-12-24"

mycars <- mtcars
mycars$name <- rownames(mycars)

ggplot(mycars, aes(wt, mpg, label = name)) +
  geom_text(aes(size = wt), nudge_x = -0.1, hjust = "right")
#> Error in 1 - hjust[is_case]: non-numeric argument to binary operator

ggplot(mycars, aes(wt, mpg, label = name)) +
  geom_text(nudge_x = -0.1, hjust = "right")

ggplot(mycars, aes(wt, mpg, label = name)) +
  geom_text(aes(size = wt), nudge_x = -0.1, hjust = 1)

^{Created on 2023-12-25 with reprex v2.0.2}

[teunbrand]

Thanks @aphalo for catching this bug. The timing is perfect as we're currently revising what new bugs we may have introduced. I think the problem is currently in the legend key code, but we should definitely fix this for the upcoming release.

[teunbrand]

Considering this fixed by #5618.