ESP8266 Telegram echo-bot throws exception

I am trying to run the echo bot example from https://github.com/CasaJasmina/TelegramBot-Library/tree/master/examples/EchoBot-ESP8266 on my ESP8266 NodeMCU using Arduino IDE 1.8.9 When Wifi is connected the serial monitor gives me the following exception:

13:48:10.135 -> WiFi connected
13:48:27.328 -> no new message
13:48:27.328 -> 
13:48:27.328 -> Exception (3):
13:48:27.328 -> epc1=0x402077c6 epc2=0x00000000 epc3=0x00000000 excvaddr=0x4006ea81 depc=0x00000000
13:48:27.328 -> 
13:48:27.328 -> >>>stack>>>
13:48:27.328 -> 
13:48:27.328 -> ctx: cont
13:48:27.328 -> sp: 3ffffd50 end: 3fffffc0 offset: 01a0
13:48:27.328 -> 3ffffef0:  3ffeecac 0000ff19 0000ff19 402078c4  
13:48:27.328 -> 3fffff00:  3fffdad0 00000000 3fffff64 40207cec  
13:48:27.328 -> 3fffff10:  3ffe85dd 3fffff70 3ffeeba4 40205cb4  
13:48:27.328 -> 3fffff20:  00000000 00000000 3ffeea78 40205cd8  
13:48:27.328 -> 3fffff30:  3fffdad0 00000000 3ffeea78 40201134  
13:48:27.362 -> 3fffff40:  000001bb 00000d50 3ffeeba4 3ffeec1c  
13:48:27.362 -> 3fffff50:  000001bb 3ffeea84 3ffe865c 3ffeec1c  
13:48:27.362 -> 3fffff60:  000001bb 3ffeea84 3ffe865c 402035bd  
13:48:27.362 -> 3fffff70:  40208748 dca79a95 40208748 dca79a95  
13:48:27.362 -> 3fffff80:  3fffdad0 3ffeeb50 3ffeea78 402042fc  
13:48:27.362 -> 3fffff90:  3fffdad0 3ffeeb50 3ffeeba4 402010b6  
13:48:27.362 -> 3fffffa0:  feefeffe 00000000 3ffeebec 40206484  
13:48:27.396 -> 3fffffb0:  feefeffe feefeffe 3ffe8558 40100461  
13:48:27.396 -> <<<stack<<<
13:48:27.396 -> 
13:48:27.396 ->  ets Jan  8 2013,rst cause:2, boot mode:(3,6)
13:48:27.396 -> 
13:48:27.396 -> load 0x4010f000, len 1384, room 16 
13:48:27.396 -> tail 8
13:48:27.396 -> chksum 0x2d
13:48:27.396 -> csum 0x2d
13:48:27.396 -> v8b899c12
13:48:27.396 -> ~ld
13:48:27.464 -> Connecting Wifi: ...
13:48:28.954 -> WiFi connected

and so on and so forth.

The bot itself seems to be working:

• one can send messages within Telegram;
• it is possible to send messages using the HTTP GET,
• it is also possible to send messages from a browser like https://api.telegram.org/bot/sendMessage?chat_id=163202456&text=message-sent-from-browser)

What I will do next is to find out the "rst cause": https://www.espressif.com/sites/default/files/documentation/esp8266_reset_causes_and_common_fatal_exception_causes_en.pdf

Does anyone have an idea how to investigate further?