This fixes a bug when playing music on the music info screen that is
not configured in "musicinfo.conf", therefore getting a negative ID,
which caused an illegal array access when checking for music loop.
(The added range check takes into account that the default loop mode
for sounds is "false", but is "true" for music, if not specified.)
#define IS_NEW_FRAME(f, g) (IS_ANIMATED(g) && IS_NEW_DELAY(f, g))
#define IS_NEXT_FRAME(f, g) (IS_NEW_FRAME(f, g) && (f) > 0)
-#define IS_LOOP_SOUND(s) (sound_info[s].loop)
-#define IS_LOOP_MUSIC(s) (music_info[s].loop)
+#define IS_LOOP_SOUND(s) ((s) >= 0 && sound_info[s].loop)
+#define IS_LOOP_MUSIC(s) ((s) < 0 || music_info[s].loop)
#define IS_SPECIAL_GFX_ARG(a) ((a) >= 0 && (a) < NUM_SPECIAL_GFX_ARGS)