hive plot fails with unused factors

[mkoohafkan]

library(tidygraph)
library(ggraph)
flareGr <- as_tbl_graph(flare$imports) %>%
  mutate(
    type = dplyr::case_when(
      centrality_degree(mode = 'in') == 0 ~ 'Source',
      centrality_degree(mode = 'out') == 0 ~ 'Sink',
      TRUE ~ 'Both'
    )
  ) %>%
  activate(edges) %>%
  mutate(
    type = dplyr::case_when(
      grepl('flare.analytics', paste(.N()$name[from], .N()$name[to])) ~ 'Analytics',
      TRUE ~ 'Other'
    )
  )

# works
ggraph(flareGr, 'hive', axis = type) +
  geom_edge_hive(aes(colour = type), edge_alpha = 0.1) +
  geom_axis_hive(aes(colour = type)) +
  coord_fixed()

# works
flareGr2 <- flareGr %N>% mutate(type = factor(type))
ggraph(flareGr2, 'hive', axis = type) +
  geom_edge_hive(aes(colour = type), edge_alpha = 0.1) +
  geom_axis_hive(aes(colour = type)) +
  coord_fixed()

# does not work
flareGr3 <- flareGr %N>% mutate(type = factor(type, c("Source", "Sink", "Both", "Neither")))
ggraph(flareGr3, 'hive', axis = type) +
  geom_edge_hive(aes(colour = type), edge_alpha = 0.1) +
  geom_axis_hive(aes(colour = type)) +
  coord_fixed()

Error: Elements must equal the number of rows or 1