Fix another crash on page 2 of spell picker

src/game/boe.party.cpp

@@ -1572,6 +1572,7 @@ bool pc_can_cast_spell(const cPlayer& pc,eSkill type) {
 }
 
 bool pc_can_cast_spell(const cPlayer& pc,eSpell spell_num) {
+	if(spell_num == eSpell::NONE) return false;
 	short level,store_w_cast;
 	eSkill type = (*spell_num).type;