nil check when calculation excavation

Author: nh6574

JoyousSpring.json

@@ -8,6 +8,6 @@
   "main_file": "JoyousSpring.lua",
   "priority": 0,
   "badge_colour": "F4A6C7",
-  "version": "0.8.5.3",
+  "version": "0.8.5.4",
   "dependencies": ["Steamodded (>=1.0.0~BETA-0827b)", "Lovely (>=0.8.0)"]
 }

src/effects.lua

@@ -544,6 +544,7 @@ JoyousSpring.excavate = function(amount, context)
 end
 
 JoyousSpring.calculate_excavate = function(context)
+    if not G.jokers or not G.jokers.cards then return end
     local maxlimit = 0
     for _, joker in ipairs(G.jokers.cards) do
         if not joker.debuff and joker.config.center.joy_calculate_excavate then