fix: 修正技能升级数据空值检查逻辑

将空值合并运算符(??)替换为三元条件运算符，确保当SkillUpList[s_uuid]为0或false时也能正确使用默认值SkillUpList[1001]。同时移除未使用的sNum变量计算。

assets/script/game/hero/SCastSystem.ts

@@ -110,7 +110,7 @@ export class SCastSystem extends ecs.ComblockSystem implements ecs.ISystemUpdate
         const s_uuid = castPlan.skillId;
         const skillLv = castPlan.skillLv;
         const config = SkillSet[s_uuid];
-        const sUp = SkillUpList[s_uuid] ?? SkillUpList[1001];
+        const sUp = SkillUpList[s_uuid] ? SkillUpList[s_uuid]:SkillUpList[1001];
         const cNum = Math.min(2, Math.max(0, Math.floor(sUp.num ?? 0)));
         if (!config) return;
         //播放前摇技能动画
@@ -164,7 +164,6 @@ export class SCastSystem extends ecs.ComblockSystem implements ecs.ISystemUpdate
         const parent = caster.node.parent;
         if (!parent) return;
         const skill = ecs.getEntity<Skill>(Skill);
-        const sNum= Math.floor(SkillUpList[s_uuid].num*skillLv)
         const startPos = this.resolveRepeatCastStartPos(caster.node.position, castIndex);
         skill.load(startPos, parent, s_uuid, targetPos.clone(), caster, cAttrsComp, skillLv, 0);
     }