limit _async_service_task watchdog to guard only recv/poll callbacks

others are not critical and could skip setting/removing watchdog each time

src/AsyncTCP.cpp

@@ -175,7 +175,7 @@ static inline bool _get_async_event(lwip_event_packet_t** e) {
       if (xQueueReceive(_async_queue, &next_pkt, 0) == pdPASS){
         free(next_pkt);
         next_pkt = NULL;
-        log_w("coalescing polls, async callback might be too slow!");
+        log_d("coalescing polls, async callback might be too slow!");
       } else
         return true;
     } else
@@ -259,15 +259,23 @@ static void _async_service_task(void* pvParameters) {
   for (;;) {
     if (_get_async_event(&packet)) {
 #if CONFIG_ASYNC_TCP_USE_WDT
-      if (esp_task_wdt_add(NULL) != ESP_OK) {
-        log_e("Failed to add async task to WDT");
+      switch((size_t)packet->arg){
+        case LWIP_TCP_RECV:
+        case LWIP_TCP_POLL:
+          if (esp_task_wdt_add(NULL) != ESP_OK) {
+            log_e("Failed to add async task to WDT");
+          }
+          _handle_async_event(packet);
+          if (esp_task_wdt_delete(NULL) != ESP_OK) {
+            log_e("Failed to remove async task from WDT");
+          }
+          break;
+
+        default:
+          _handle_async_event(packet);
       }
-#endif
+#else
       _handle_async_event(packet);
-#if CONFIG_ASYNC_TCP_USE_WDT
-      if (esp_task_wdt_delete(NULL) != ESP_OK) {
-        log_e("Failed to remove loop task from WDT");
-      }
 #endif
     }
   }