[SQUASH ME]

Edits from review

Author: jkbonfield

cram/cram_decode.c

@@ -2390,8 +2390,8 @@ int cram_decode_slice(cram_fd *fd, cram_container *c, cram_slice *s,
 
     if ((fd->required_fields & SAM_SEQ) &&
         s->ref == NULL && s->hdr->ref_seq_id >= 0 && !c->comp_hdr->no_ref) {
-        hts_log_error("Unable to fetch reference #%d:%"PRId64"-%"PRId64"\n",
-                      ref_id, s->hdr->ref_seq_start,
+        hts_log_error("Unable to fetch reference %s:%"PRId64"-%"PRId64,
+                      fd->refs->ref_id[ref_id]->name, s->hdr->ref_seq_start,
                       s->hdr->ref_seq_start + s->hdr->ref_seq_span-1);
         return -1;
     }

cram/cram_io.c

@@ -3440,7 +3440,9 @@ char *cram_get_ref(cram_fd *fd, int id, hts_pos_t start, hts_pos_t end) {
             hts_log_warning("Reference file given, but ref '%s' not present",
                             r->name);
         if (cram_populate_ref(fd, id, r) == -1) {
-            hts_log_warning("Failed to populate reference for id %d", id);
+            hts_log_warning("Failed to populate reference \"%s\"",
+                            r->name);
+            hts_log_warning("See https://www.htslib.org/doc/reference_seqs.html for further suggestions");
             pthread_mutex_unlock(&fd->refs->lock);
             pthread_mutex_unlock(&fd->ref_lock);
             return NULL;