Fix crash on seeing a monster

osx/boe.graphutil.cpp

@@ -318,6 +318,7 @@ void play_see_monster_str(unsigned short m){
 	snd = scenario.scen_monsters[m].see_sound;
 	spec = scenario.scen_monsters[m].see_spec;
 	// First display strings, if any
+	if(str1 || str2) {
 		cStrDlog display_strings(str1 ? scenario.monst_strs[str1] : "", str2 ? scenario.monst_strs[str2] : "", "", pic, type, NULL);
 		display_strings.setSound(snd);
 		display_strings.setRecordHandler(cStringRecorder()
@@ -325,6 +326,7 @@ void play_see_monster_str(unsigned short m){
 			.string2(NOTE_MONST, m, 1)
 		);
 		display_strings.show();
+	}
 	// Then run the special, if any
 	if(spec > -1){
 		for(int i = 2; i < 20; i++){