Fix exception 28 when unable to send MQTT message

Fix exception 28 when unable to send MQTT message and a topic name without a slash '/' (#12555)

CHANGELOG.md

@@ -23,6 +23,8 @@ All notable changes to this project will be documented in this file.
 - Scripter moving average and sml input validation (#12541)
 - Zigbee Hue angle encoding (#12545)
 - AM2320 value reporting (#12552)
+- Exception 28 when unable to send MQTT message and a topic name without a slash '/' (#12555)
+- Wi-Fi initial setup workaround for 11n only routers (#12566)
 
 ## [9.5.0.1] 20210701
 ### Added

RELEASENOTES.md

@@ -126,6 +126,8 @@ The latter links can be used for OTA upgrades too like ``OtaUrl http://ota.tasmo
 - Scripter and Display MQTT errors due to MQTT_DATA move to String [#12525](https://github.com/arendst/Tasmota/issues/12525)
 - Scripter moving average and sml input validation [#12541](https://github.com/arendst/Tasmota/issues/12541)
 - Zigbee Hue angle encoding [#12545](https://github.com/arendst/Tasmota/issues/12545)
+- Exception 28 when unable to send MQTT message and a topic name without a slash '/' [#12555](https://github.com/arendst/Tasmota/issues/12555)
+- Wi-Fi initial setup workaround for 11n only routers [#12566](https://github.com/arendst/Tasmota/issues/12566)
 
 ### Noted
 - ESP32 single core **tasmota32solo1.bin** binary can only be uploaded using the GUI as OTA upload will trigger the watchdog timer

tasmota/xdrv_02_9_mqtt.ino

@@ -640,7 +640,8 @@ void MqttPublishPayload(const char* topic, const char* payload, uint32_t binary_
     log_data_topic += topic;                             // stat/tasmota/STATUS2
   } else {
     log_data_topic = F(D_LOG_RESULT);                    // RSL:
-    log_data_topic += strrchr(topic,'/')+1;              // STATUS2
+    char *command = strrchr(topic, '/');                 // If last part of topic it is always the command
+    log_data_topic += (command == nullptr) ? topic : command +1;  // STATUS2
     retained = false;                                    // Without MQTT enabled there is no retained message
   }
   log_data_topic += F(" = ");                            // =