e_band()'s upper line is incorrect

[shrektan]

See the example below.

library(echarts4r)
df <- data.frame(
  x = 1:10,
  y = runif(10, 5, 10)
) %>%
  dplyr::mutate(
    lwr = y - 2,
    upr = y + 2
  )

df %>%
  e_charts(x) %>%
  e_line(y) %>%
  e_band(lwr, upr)