Don't crash when a response is not defined

doc/UPDATES.md

@@ -4,6 +4,7 @@
   * Bots now share channel key to other bots even if not opped.
   * Fix rare issue with writing binary config.
   * Make ./wraith -q and -Q clearly exit when already written.
+  * Don't crash when looking up a missing response.
 
 # 1.4.9
   * Fix various compile warnings and spam

src/response.cc

@@ -25,6 +25,8 @@ init_responses()
 const char *
 response(response_t type)
 {
+  if (!res_map.contains(type))
+    return type;
   return res_map[type].at(randint(res_map[type].size()));
 }
 /* vim: set sts=2 sw=2 ts=8 et: */