From c3bed806a1ba7c54aae09020701ab28c9ab05727 Mon Sep 17 00:00:00 2001
From: Pedro Aphalo <pedro.aphalo@helsinki.fi>
Date: Fri, 29 Dec 2023 00:59:37 +0200
Subject: [PATCH] Add message to stopifnot() call

---
 R/spct.conversion.R | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/R/spct.conversion.R b/R/spct.conversion.R
index 63d0936f..6b6dca72 100644
--- a/R/spct.conversion.R
+++ b/R/spct.conversion.R
@@ -51,7 +51,8 @@ cps2irrad <- function(x.sample,
     x.sample <- pre.fun(x.sample, ...)
   }
   cps.col.sample <- grep("^cps", names(x.sample), value = TRUE)
-  stopifnot(length(cps.col.sample) == 1)
+  stopifnot("Multiple 'cps' columns found when one expected" =
+              length(cps.col.sample) == 1)
   z <- as.generic_spct(x.sample)
   z[[cps.col.sample]] <- NULL
   z[["s.e.irrad"]] <- x.sample[[cps.col.sample]] * irrad.mult