fix: defer ch390 exti until rtos is ready

Core/Src/stm32f1xx_it.c

@@ -2,6 +2,7 @@
 #include "stm32f1xx_it.h"
 
 #include "FreeRTOS.h"
+#include "semphr.h"
 #include "task.h"
 
 #include "app_runtime.h"
@@ -101,8 +102,11 @@ void EXTI0_IRQHandler(void)
 
     if (__HAL_GPIO_EXTI_GET_IT(GPIO_PIN_0) != RESET) {
         __HAL_GPIO_EXTI_CLEAR_IT(GPIO_PIN_0);
-        xSemaphoreGiveFromISR(xNetSemaphore, &xHigherPriorityTaskWoken);
-        portYIELD_FROM_ISR(xHigherPriorityTaskWoken);
+        if ((xNetSemaphore != NULL) &&
+            (xTaskGetSchedulerState() == taskSCHEDULER_RUNNING)) {
+            xSemaphoreGiveFromISR(xNetSemaphore, &xHigherPriorityTaskWoken);
+            portYIELD_FROM_ISR(xHigherPriorityTaskWoken);
+        }
     }
 }