Update notes fix potential nil error

NOTES.org

@@ -6,9 +6,10 @@ http://www.utf8-chartable.de/unicode-utf8-table.pl?utf8=0x
 ** DONE Get bearlibterminal autowrapped and basic window working.
 CLOSED: [2016-01-01 Fri 22:52]
 ** High Priority
-*** TODO Tweak health, regen, and damage values.
-*** TODO Fix mana being allowed to go negative.
 *** TODO Add instructions page (auto show after start, h key to show later)
+*** TODO Tweak health, regen, and damage values.
+*** DONE Fix mana being allowed to go negative.
+CLOSED: [2016-01-12 Tue 19:31]
 *** DONE Add status line section for current attack
 CLOSED: [2016-01-12 Tue 18:52]
 *** DONE Create enemy AI

src/crypts-and-corpses.lisp

@@ -98,7 +98,8 @@
   (apply 'values (mapcar #'parse-integer (split-sequence #\x (terminal-get "window.size" "0x0")))))
 
 (defun calc-location (x y map)
-  (+ (* (game-map-width map) y) x))
+  (when x y map
+        (+ (* (game-map-width map) y) x)))
 
 (defgeneric set-location (object x y map))
 (defmethod set-location ((object tile-entity) x y map)