docs: update kavaref-core

Author: fankes

docs-source/src/en/library/kavaref-core.md

@@ -489,6 +489,25 @@ but we **do not recommend this**, which will mask the problem unless it is neces
 If you set `optional()`, please do not use `firstMethod`, `firstConstructor` and other methods to get a single result.
 Because they throw an exception with empty list when there is no result, you can use the method with the suffix `OrNull` to get a single result.
 
+But one thing you need to pay attention to here is that if you do not set `optional()`,
+then methods such as `firstMethodOrNull` will still throw exceptions when there is no result**, which is the expected behavior because `method { ... }`
+This is the "build" operation of the filter. Exceptions are handled here.
+Methods such as `firstMethodOrNull` are just an encapsulation.
+It is an exception handling of Kotlin's own standard library whether the result `List` is empty. It does not participate in exception handling of KavaRef filters.
+
+So you must do it like the following.
+
+> The following example
+
+```kotlin
+Test::class.resolve()
+    // Set optional conditions.
+    .optional()
+    .firstMethodOrNull {
+        name = "doNonExistentMethod"
+    } // Return MethodResolver or null.
+```
+
 :::
 
 ### Log Management

docs-source/src/zh-cn/library/kavaref-core.md

@@ -474,6 +474,22 @@ No method found matching the condition for current class.
 如果你设置了 `optional()`，那么请不要使用 `firstMethod`、`firstConstructor` 等方法来获取单个结果，
 因为它们会在没有结果时抛出列表为空的异常，你可以使用后缀为 `OrNull` 的方法来获取单个结果。
 
+但是这里需要注意一个事情，**如果你没有设置 `optional()`，那么 `firstMethodOrNull` 等方法依然会在没有结果时抛出异常**，这是预期行为，因为 `method { ... }`
+才是过滤器的 “构建” 操作，异常在此处理，`firstMethodOrNull` 等方法只是一个封装，是对结果 `List` 是否为空的 Kotlin 自身标准库异常处理，不参与 KavaRef 过滤器的异常处理。
+
+所以你一定要像下面这样做。
+
+> 示例如下
+
+```kotlin
+Test::class.resolve()
+    // 设置可选条件
+    .optional()
+    .firstMethodOrNull {
+        name = "doNonExistentMethod"
+    } // 返回 MethodResolver 或 null
+```
+
 :::
 
 ### 日志管理