Apply suggestions from code review

Co-authored-by: Michael Chirico <[email protected]>

Author: jangorecki

R/froll.R

@@ -135,9 +135,9 @@ frolladapt = function(x, n, align="right", partial=FALSE, give.names=FALSE) {
   if (!identical(align, "right"))
     stopf("'align' other than 'right' has not yet been implemented")
   if (!isTRUEorFALSE(partial))
-    stopf("'partial' must be TRUE or FALSE")
+    stopf("'%s' must be TRUE or FALSE", "partial")
   if (!isTRUEorFALSE(give.names))
-    stopf("'give.names' must be TRUE or FALSE")
+    stopf("'%s' must be TRUE or FALSE", "give.names")
 
   if (length(n) == 1L) {
     ans = .Call(Cfrolladapt, x, n, partial)

src/frollR.c

@@ -216,7 +216,7 @@ SEXP frolladapt(SEXP xobj, SEXP kobj, SEXP partial) {
   int n = INTEGER(kobj)[0];
   if (n < 1L)
     error(_("'n' must be positive integer values (>= 1)"));
-  int *x = INTEGER(xobj);
+  int *x = INTEGER_RO(xobj);
   int64_t len = XLENGTH(xobj); // can be 0
 
   if (len && x[0] == NA_INTEGER)