Adjusted minimum vit_penalty_num config to 1 to avoid potential crash

* To disable this feature, just set vit_penalty_type to 0 is enough!

src/map/battle.c

@@ -8016,7 +8016,7 @@ static const struct _battle_data {
 	{ "vit_penalty_target",                 &battle_config.vit_penalty_target,              BL_PC,  BL_NUL, BL_ALL,         },
 	{ "vit_penalty_type",                   &battle_config.vit_penalty_type,                1,      0,      2,              },
 	{ "vit_penalty_count",                  &battle_config.vit_penalty_count,               3,      2,      INT_MAX,        },
-	{ "vit_penalty_num",                    &battle_config.vit_penalty_num,                 5,      0,      INT_MAX,        },
+	{ "vit_penalty_num",                    &battle_config.vit_penalty_num,                 5,      1,      INT_MAX,        },
 	{ "weapon_defense_type",                &battle_config.weapon_defense_type,             0,      0,      INT_MAX,        },
 	{ "magic_defense_type",                 &battle_config.magic_defense_type,              0,      0,      INT_MAX,        },
 	{ "skill_reiteration",                  &battle_config.skill_reiteration,               BL_NUL, BL_NUL, BL_ALL,         },