Croak if SUBST: argument is malformed.

git-svn-id: https://crawl-ref.svn.sourceforge.net/svnroot/crawl-ref/trunk@1682 c06c8d41-db1a-0410-9941-cceddc491573

1 files changed, 7 insertions, 2 deletions

diff --git a/crawl-ref/source/mapdef.cc b/crawl-ref/source/mapdef.cc
index dc3e9bf384..a8044f1952 100644
--- a/crawl-ref/source/mapdef.cc
+++ b/crawl-ref/source/mapdef.cc
@@ -112,8 +112,13 @@ static std::string split_key_item(const std::string &s,
     std::string substitute    = trimmed_string(s.substr(sep + 1));
 
     if (what_to_subst.length() != 1)
-        return make_stringf("selector '%s' must be exactly one character",
-                            what_to_subst.c_str());
+        return make_stringf(
+            "selector '%s' must be exactly one character in '%s'",
+            what_to_subst.c_str(), s.c_str());
+
+    if (substitute.empty())
+        return make_stringf("no substitute defined in '%s'",
+                            s.c_str());
 
     *key = what_to_subst[0];
     *arg = substitute;