fix: handle undefined state/obj in mana calculations to prevent runtime error

src/lib/game/utils/mana-utils.ts

@@ -12,8 +12,8 @@ export function computeMaxMana(
   const pu = state.prestigeUpgrades;
   const base = 
     100 +
-    (state.skills.manaWell || 0) * 100 +
-    (pu.manaWell || 0) * 500;
+    ((state.skills || {}).manaWell || 0) * 100 +
+    ((pu || {}).manaWell || 0) * 500;
   
   // Apply upgrade effects if provided
   if (effects) {
@@ -34,9 +34,9 @@ export function computeRegen(
   const temporalBonus = 1 + (pu.temporalEcho || 0) * 0.1;
   const base =
     2 +
-    (state.skills.manaFlow || 0) * 1 +
-    (state.skills.manaSpring || 0) * 2 +
-    (pu.manaFlow || 0) * 0.5;
+    ((state.skills || {}).manaFlow || 0) * 1 +
+    ((state.skills || {}).manaSpring || 0) * 2 +
+    ((pu || {}).manaFlow || 0) * 0.5;
   
   let regen = base * temporalBonus;
   
@@ -90,8 +90,8 @@ export function computeEffectiveRegen(
 export function computeClickMana(state: Pick<GameState, 'skills'>): number {
   return (
     1 +
-    (state.skills.manaTap || 0) * 1 +
-    (state.skills.manaSurge || 0) * 3
+    ((state.skills || {}).manaTap || 0) * 1 +
+    ((state.skills || {}).manaSurge || 0) * 3
   );
 }