ensure if exposure not set then plotting works

Author: wjchulme

analysis/km.R

@@ -470,9 +470,18 @@ if(smooth){
 km_plot <- function(.data) {
 
   data_with_time0 <-
+  if(length(exposure)>0L){
     .data |>
+      mutate(
+        "{exposure}" := as.factor(!!!exposure_syms)
+      )
+  } else {
+    .data
+  }
+
+  data_with_time0 <-
+    data_with_time0 |>
     mutate(
-      "{exposure}" := as.factor(!!!exposure_syms),
       lagtime = lag(time, 1, 0), # assumes the time-origin is zero
     ) %>%
     group_modify(
@@ -486,6 +495,7 @@ km_plot <- function(.data) {
         .before = 0
       )
     )
+
   ggplot_init <- if(length(exposure)==0L){
     ggplot(data_with_time0)
   } else {