fix: handle Yarn initial variable storage fallback

Assets/Scripts/Game Loop/StorageSystem.cs

@@ -146,10 +146,45 @@ namespace AibisDream
                 }
             }
 
+            if (TryGetInitialValue(variableName, out result))
+            {
+                return true;
+            }
+
             result = default;
             return false;
         }
 
+        private bool TryGetInitialValue<T>(string variableName, out T result)
+        {
+            result = default;
+
+            if (Program == null || !Program.InitialValues.TryGetValue(variableName, out var initialValue))
+            {
+                return false;
+            }
+
+            if (!InitialValueMatchesType<T>(initialValue.ValueCase))
+            {
+                return false;
+            }
+
+            return Program.TryGetInitialValue(variableName, out result);
+        }
+
+        private static bool InitialValueMatchesType<T>(Yarn.Operand.ValueOneofCase valueCase)
+        {
+            var targetType = typeof(T);
+
+            return valueCase switch
+            {
+                Yarn.Operand.ValueOneofCase.BoolValue => targetType == typeof(bool),
+                Yarn.Operand.ValueOneofCase.StringValue => targetType == typeof(string),
+                Yarn.Operand.ValueOneofCase.FloatValue => targetType == typeof(float),
+                _ => false
+            };
+        }
+
         #endregion
 
         #region 序列化
@@ -365,4 +400,4 @@ namespace AibisDream
         public string variableName;
         public object value;
     }
-}
+}