computation failed in 60stat flow 28 29 60 3a

1ggplot(df_data_Aluv,
2           aes(x = month, 
3               stratum = Job, 
4               alluvium = Employee,
5               y = freq,
6               fill = Job, 
7               label = Job)) +
8        scale_x_discrete(expand = c(.1, .1)) +
9        geom_flow(stat = "alluvium", 
10                  lode.guidance = "frontback",
11                  color = "darkgray") +
12        geom_stratum(alpha = .5) +
13        geom_text(stat = "stratum", size = 3) +
14        theme(legend.position = "bottom") +
15        ggtitle("Project month responses at three points in time")

1    df_data_Aluv <- data %>%
2        filter(PostDate >= "2019-08-01" & PostDate <= "2019-10-30") %>%
3        select(date = PostDate, Employee, Job, Hours) %>%
4        group_by(Job, month = as.character(floor_date(date, "month")), Employee) %>%
5        summarize(freq = n_distinct(Employee), Hours = sum(Hours)) %>%
6        mutate(empmon = paste(Employee, " -- ", month)) %>%
7        group_by(empmon) %>%
8        filter(Hours == max(Hours)) %>%
9        distinct(empmon, .keep_all = TRUE)