错误：连续值提供给离散刻度4

Question

我正在努力为图表添加颜色，但我不断收到错误消息：

continuous value supplied to discrete scale

这是我正在使用的代码：

ggplot(by_team_mean_score1) +
  geom_col(mapping = aes(x = reorder(team1, mean_score1), y = mean_score1))+
  theme(axis.text.x = element_text(angle = 60, hjust = 1)) +
  ggtitle("Mean No. of Home Goals") +
  xlab("Team") +
  ylab("Mean No. Home Goals")