invalid factor level, NA generated

General
1

Hello,

I'm trying to create a new variable 'value' in the data frame, and assign either the value of its corresponding 'src' or 'dst' if 'group' is either 'A' or 'B'. But I get 'NA' in 'B' instead of 'C1' ('dst') with a warning of ': invalid factor level, NA generated'

Could anyone help me to understand what the issue is with the factors here?
What am I doing wrong and what is the right way to do it?

Many thanks in advance,

library(tidyverse)
#> Warning: package 'ggplot2' was built under R version 3.6.2

dF <- data.frame(
  group = c("A","A","B"),
  src = c("O1","O2", "O3"),
  dst = c("C1","C2","C1")
)

dF <- dF %>%
  mutate(
    value = group == "A",
    value = if_else(value == TRUE, src, dst)
  )
#> Warning in `[<-.factor`(`*tmp*`, i, value = structure(1L, .Label =
#> c("C1", : invalid factor level, NA generated

dF
#>   group src dst value
#> 1     A  O1  C1    O1
#> 2     A  O2  C2    O2
#> 3     B  O3  C1  <NA>

Created on 2021-07-14 by the reprex package (v2.0.0)