diff --git a/source/mijin/async/coroutine.hpp b/source/mijin/async/coroutine.hpp
index f77386f..36f0284 100644
--- a/source/mijin/async/coroutine.hpp
+++ b/source/mijin/async/coroutine.hpp
@@ -416,6 +416,11 @@ public:
     TaskHandle& operator=(const TaskHandle&) = default;
     TaskHandle& operator=(TaskHandle&&) = default;
 
+    [[nodiscard]] bool isValid() const noexcept
+    {
+        return !state_.expired();
+    }
+
     void cancel() const noexcept
     {
         if (std::shared_ptr<TaskSharedState> state = state_.lock())
diff --git a/source/mijin/debug/assert.hpp b/source/mijin/debug/assert.hpp
index 336cf6c..44bea03 100644
--- a/source/mijin/debug/assert.hpp
+++ b/source/mijin/debug/assert.hpp
@@ -56,15 +56,15 @@ if (!static_cast<bool>(condition))
     /* static bool ignoreAll = false; */                                           \
     if (true) /*!ignoreAll */                                                      \
     {                                                                              \
-        mijin::AssertionResult assertion_result__ = mijin::handleAssert(#condition,\
-                msg, MIJIN_FUNC(), __FILE__, __LINE__);                            \
+        const mijin::AssertionResult assertion_result__ = mijin::handleAssert(     \
+                #condition, msg, MIJIN_FUNC(), __FILE__, __LINE__);                \
         switch (assertion_result__)                                                \
         {                                                                          \
         case mijin::AssertionResult::ABORT:                                        \
             std::abort();                                                          \
             break;                                                                 \
         case mijin::AssertionResult::IGNORE:                                       \
-            break;                                                                 \
+            /*break*/;                                                             \
         case mijin::AssertionResult::IGNORE_ALL:                                   \
             /* ignoreAll = true; */                                                \
             break;                                                                 \