ggplot2 with summarize as y aesthetic - r

Here's my task:

Create the following graph:

• Group the Pokemon data by type1 and is_legendary
• Summarize the data with the mean of the attack
• Create a bar chart with type1 on the x, the mean of the attack on the y and type one of the fill
• Change the colors of the type one to be type_color
• facet_wrap it so that there are different bar charts for the regular and legendary pokemon

I am able to summarize the data by the mean of the attack, but it is not a column in my dataset. How do I make it so the mean of the attack is the y aesthetic? Am I overlooking a simpler way?

I have tried making a new column on the original Pokemon dataset, but that would create a mean of all of the data and not group it by type1 or is_legendary.

I also keep getting the error: Error: stat_count() must not be used with a y aesthetic. But when I look up that error, I can't see how it applies to this particular issue.

pokemon$type1 <- factor(pokemon$type1)
pokemon$is_legendary <- factor(pokemon$is_legendary)

pokemon %>% 
  group_by(type1, is_legendary) %>%  
  summarize(mean_attack = mean(attack)) %>% 
  ggplot(mapping = aes(x = type1, y = mean_attack, fill = type1)) + geom_bar() 
+ scale_fill_manual(values = type_color) + facet_wrap(~ is_legendary) 
+ labs(title = "Average Attack of Legendary and Regular Pokemon") + pokemon.theme