[Bug]: Accessing columns by path doesn't work when table has an overall column.

Using the example found here (minus the secondary column splitting split_cols_by("SEX")):

.simpleCap <- function(x) {
  if (length(x) > 1) {
    return(sapply(x, .simpleCap))
  }
  s <- strsplit(tolower(x), " ")[[1]]
  paste(toupper(substring(s, 1, 1)), substring(s, 2), sep = "", collapse = " ")
}

adsl2 <- ex_adsl |>
  filter(SEX %in% c("M", "F") & RACE %in% (levels(RACE)[1:3])) |>
  mutate(ethnicity = .simpleCap(gsub("(.*)OR.*", "\\1", RACE)), RACE = factor(RACE))

lyt2 <- basic_table() |>
  split_cols_by("ARM") |>
  split_rows_by("RACE", labels_var = "ethnicity", split_fun = drop_split_levels) |>
  summarize_row_groups() |>
  analyze(c("AGE", "STRATA1"))

tbl2 <- build_table(lyt2, adsl2)

tbl2
#             A: Drug X    B: Placebo   C: Combination
# ————————————————————————————————————————————————————
# Asian       66 (54.1%)   66 (55.5%)     71 (59.2%)  
#   AGE                                               
#     Mean      32.50        36.68          36.99     
#   STRATA1                                           
#     A           21           24             18      
#     B           20           22             25      
#     C           25           20             28      
# Black       30 (24.6%)   28 (23.5%)     28 (23.3%)  
#   AGE                                               
#     Mean      34.27        34.93          33.71     
#   STRATA1                                           
#     A           7            11             10      
#     B           11           7              8       
#     C           12           10             10      
# White       26 (21.3%)   25 (21.0%)     21 (17.5%)  
#   AGE                                               
#     Mean      36.15        33.12          31.95     
#   STRATA1                                           
#     A           8            6              8       
#     B           9            12             7       
#     C           9            7              6 

Adding a column footnote works for this, for example:

col_paths_summary(tbl2)
# label             path               
# —————————————————————————————————————
# A: Drug X         ARM, A: Drug X     
# B: Placebo        ARM, B: Placebo    
# C: Combination    ARM, C: Combination

fnotes_at_path(tbl2, rowpath = NULL, c("ARM", "B: Placebo")) <- c("this is a placebo")
tbl2
#             A: Drug X    B: Placebo {1}   C: Combination
# ————————————————————————————————————————————————————————
# Asian       66 (54.1%)     66 (55.5%)       71 (59.2%)  
#   AGE                                                   
#     Mean      32.50          36.68            36.99     
# ...
#     C           9              7                6       
# ————————————————————————————————————————————————————————

# {1} - this is a placebo
# ————————————————————————————————————————————————————————

However, if we add an overall column, this no longer works:

lyt3 <- lyt2 |> add_overall_col("Total")
tbl3 <- build_table(lyt3, adsl2)
tbl3
#             A: Drug X    B: Placebo   C: Combination      Total   
# ——————————————————————————————————————————————————————————————————
# Asian       66 (54.1%)   66 (55.5%)     71 (59.2%)     203 (56.2%)
#   AGE                                                             
#     Mean      32.50        36.68          36.99           35.43   
# ...
#     C           9            7              6              22  

col_paths_summary(tbl3)
# label             path               
# —————————————————————————————————————
# A: Drug X         ARM, A: Drug X     
# B: Placebo        ARM, B: Placebo    
# C: Combination    ARM, C: Combination
# Total             Total, Total

fnotes_at_path(tbl3, rowpath = NULL, c("ARM", "B: Placebo")) <- c("this is a placebo")
# Error in col_fnotes_at_path(coltree(ttrp), colpath, fnotes = value) : 
#   Path appears invalid at step: ARM

Also, possibly related, note that the actual example found here has its footnote numbered as NA in the output found in the article.

I encounter this using rtables 0.6.9 installed from CRAN as well as v0.6.9.9005 installed from GitHub.

Reproduce the failure with the issue's lyt3, build_table, col_paths_summary, and fnotes_at_path example, starting by comparing the column paths before and after add_overall_col("Total"). Trace how fnotes_at_path resolves the requested ARM path when the overall column is present; done means the placebo footnote attaches successfully and the related footnote numbering issue is clarified or fixed.