fix: crash after deconstruction #423

Author: lijy91

example/windows/flutter/CMakeLists.txt

@@ -9,6 +9,11 @@ include(${EPHEMERAL_DIR}/generated_config.cmake)
 # https://github.com/flutter/flutter/issues/57146.
 set(WRAPPER_ROOT "${EPHEMERAL_DIR}/cpp_client_wrapper")
 
+# Set fallback configurations for older versions of the flutter tool.
+if (NOT DEFINED FLUTTER_TARGET_PLATFORM)
+  set(FLUTTER_TARGET_PLATFORM "windows-x64")
+endif()
+
 # === Flutter Library ===
 set(FLUTTER_LIBRARY "${EPHEMERAL_DIR}/flutter_windows.dll")
 
@@ -91,7 +96,7 @@ add_custom_command(
   COMMAND ${CMAKE_COMMAND} -E env
     ${FLUTTER_TOOL_ENVIRONMENT}
     "${FLUTTER_ROOT}/packages/flutter_tools/bin/tool_backend.bat"
-      windows-x64 $<CONFIG>
+      ${FLUTTER_TARGET_PLATFORM} $<CONFIG>
   VERBATIM
 )
 add_custom_target(flutter_assemble DEPENDS

windows/window_manager_plugin.cpp

@@ -92,9 +92,11 @@ WindowManagerPlugin::WindowManagerPlugin(
 
 WindowManagerPlugin::~WindowManagerPlugin() {
   registrar->UnregisterTopLevelWindowProcDelegate(window_proc_id);
+  channel = nullptr;
 }
 
 void WindowManagerPlugin::_EmitEvent(std::string eventName) {
+  if (channel == nullptr) return;
   flutter::EncodableMap args = flutter::EncodableMap();
   args[flutter::EncodableValue("eventName")] =
       flutter::EncodableValue(eventName);