add client disconnect reason text in SocketIOclient events (#971)

* add client disconnect reason text in SocketIOclient events

Author: kumv-net

src/SocketIOclient.cpp

@@ -188,8 +188,13 @@ void SocketIOclient::loop(void) {
 void SocketIOclient::handleCbEvent(WStype_t type, uint8_t * payload, size_t length) {
     switch(type) {
         case WStype_DISCONNECTED:
-            runIOCbEvent(sIOtype_DISCONNECT, NULL, 0);
-            DEBUG_WEBSOCKETS("[wsIOc] Disconnected!\n");
+            if(payload && length > 0) {
+                runIOCbEvent(sIOtype_DISCONNECT, payload, length);
+                DEBUG_WEBSOCKETS("[wsIOc] Disconnected! reason: %s\n", payload);
+            } else {
+                runIOCbEvent(sIOtype_DISCONNECT, NULL, 0);
+                DEBUG_WEBSOCKETS("[wsIOc] Disconnected!\n");
+            }
             break;
         case WStype_CONNECTED: {
             DEBUG_WEBSOCKETS("[wsIOc] Connected to url: %s\n", payload);