ESP8266 crashing on data received about umqttbroker HOT 11 OPEN

   void uMQTTBroker::_onData(uint32_t *args, const char* topic, uint32_t topic_len, const char *data, uint32_t length) {
	char *topic_str;
	
	if ((topic_str = (char *)malloc(topic_len+1)) == NULL)
	  return;

	os_memcpy(topic_str, topic, topic_len);
	topic_str[topic_len] = '\0';
	TheBroker->onData((String)topic_str, data, length);
	free(topic_str);
    }

Exception 9: LoadStoreAlignmentCause: Load or store to an unaligned address
PC: 0x40209292: uMQTTBroker::_onData(unsigned int*, char const*, unsigned int, char const*, unsigned int) at C:\Users\agierens\Documents\Arduino\libraries\uMQTTBroker-master\src\uMQTTBroker.cpp line 33
EXCVADDR: 0x666e6f6f

Decoding stack results
0x40209282: uMQTTBroker::_onData(unsigned int*, char const*, unsigned int, char const*, unsigned int) at C:\Users\agierens\Documents\Arduino\libraries\uMQTTBroker-master\src\uMQTTBroker.cpp line 32
0x40209254: uMQTTBroker::_onData(unsigned int*, char const*, unsigned int, char const*, unsigned int) at C:\Users\agierens\Documents\Arduino\libraries\uMQTTBroker-master\src\uMQTTBroker.cpp line 25
0x40209274: uMQTTBroker::_onData(unsigned int*, char const*, unsigned int, char const*, unsigned int) at C:\Users\agierens\Documents\Arduino\libraries\uMQTTBroker-master\src\uMQTTBroker.cpp line 28
0x4021c67c: ethernet_output at netif/ethernet.c line 312
0x40101238: umm_poison_free_fl(void*, char const*, int) at C:\Users\agierens\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\2.7.4\cores\esp8266\umm_malloc/umm_local.c line 149
0x40209254: uMQTTBroker::_onData(unsigned int*, char const*, unsigned int, char const*, unsigned int) at C:\Users\agierens\Documents\Arduino\libraries\uMQTTBroker-master\src\uMQTTBroker.cpp line 25
0x402367f0: publish_topic at C:\Users\agierens\Documents\Arduino\libraries\uMQTTBroker-master\src\mqtt_server.c line 65
0x40100f49: check_poison_neighbors(uint16_t) at C:\Users\agierens\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\2.7.4\cores\esp8266\umm_malloc/umm_local.c line 71
0x40101005: umm_malloc_core(size_t) at C:\Users\agierens\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\2.7.4\cores\esp8266\umm_malloc\umm_malloc.cpp line 458
0x402378cc: find_topic at C:\Users\agierens\Documents\Arduino\libraries\uMQTTBroker-master\src\mqtt_topiclist.c line 73
0x402367b4: publish_topic at C:\Users\agierens\Documents\Arduino\libraries\uMQTTBroker-master\src\mqtt_server.c line 58
0x4023751c: MQTT_ClientCon_recv_cb at C:\Users\agierens\Documents\Arduino\libraries\uMQTTBroker-master\src\mqtt_server.c line 351