Can't animate plot from ggstream

[RicardoRH96]

I'm trying to animate a muller plot but I'm having errors when doing "transition_reveal(after_stat(x))"
Reproducible example:

df <- data.frame(year = seq(1980,2023,1),
group = rep(c('group1','group2'),22),
count = runif(44, min=0, max=150))

ggplot(df, aes(year, count, fill=group)) +
geom_stream(type="ridge", color = 1, lwd=0.3, alpha=0.9, sorting = "none") +
xlab("Year") +
ylab("Count") +
transition_reveal(after_stat(x))

This is the error I'm getting:
Error in geom_stream():
! Problem while computing stat.
ℹ Error occurred in the 1st layer.
Caused by error in dplyr::left_join():
! Join columns in y must be present in the
data.
✖ Problem with group.
Run rlang::last_trace() to see where the error occurred.
Warning messages:
1: In data.frame(x = full_values$x, y = yy[, iStream * 2], group = as.integer(.group)) :
NAs introduced by coercion
2: In data.frame(x = full_values$x, y = yy[, iStream * 2], group = as.integer(.group)) :
NAs introduced by coercion