`coord_polar` causes error with `ggtext::element_markdown`

[mevers]

Originally reported as a ggtext issue here I was advised by @clauswilke to flag this here as well.

Using coord_polar with ggtext::element_markdown to theme x-axis labels causes an error

Error in grid.Call.graphics(C_setviewport, vp, TRUE) :
non-finite location and/or size for viewport

with the plot still drawn correctly.

---

A minimal & reproducible example:

df <- data.frame(name = sprintf("**%s**", LETTERS[1:4]), value = 1:4)

library(ggplot2)
library(ggtext)

ggplot(df, aes(name, value)) +
    geom_point() +
    coord_polar() +
    theme(axis.text.x = element_markdown())

Removing coord_polar gets rid of the error.

[clauswilke]

With a quick glance at the relevant code, I suspect it's caused by this line here:

ggplot2/R/coord-polar.r

Line 190 in 73256c9

bottom = draw_axis(NA, "", "bottom", theme)

It is trying to draw an empty axis by supplying NA as break position. Maybe element_markdown() needs to be able to handle that, in which case this would be a ggtext bug, not a ggplot2 bug. Still thinking about it.

[thomasp85]

NA should be supported so I'm closing this here