ESP8266 crashed on NTP error

[lunanigra]

Hello, normally everything works perfectly. But I recognized twice that the ESP8266 crashes if the NTP server is not reachable. There where several connection attempts - then after few minutes a crash. As mentioned this does not happen always - just few times.

Please find the last serial output plus stack trace below.
The crash itself is not really critical; as long as the ESP8266 will restart automatically.

Thanks, JC

Time Sync error: NTP server not reachable
Current timestamp: 193
-- NTP Server hostname: pool.ntp.org
-- Transmit NTP Request
-- NTP error :-(
Time Sync error: NTP server not reachable
Current timestamp: 198
Disconnected from SSID: xxx
Reason: 8
Disconnected from SSID: xxx
Reason: 201
Disconnected from SSID: xxx
Reason: 201
-- NTP Server hostname: pool.ntp.org
-- NTP Error. WiFi not connected.
Time Sync error: NTP server not reachable
-- NTP Server hostname: pool.ntp.org
-- NTP Error. WiFi not connected.
Time Sync error: NTP server not reachable
-- NTP Server hostname: pool.ntp.org
-- NTP Error. WiFi not connected.
Time Sync error: NTP server not reachable

Exception (28):
epc1=0x4020abbb epc2=0x00000000 epc3=0x00000000 excvaddr=0x00000004 depc=0x00000000

ctx: sys 
sp: 3fff0970 end: 3fffffb0 offset: 01a0

>>>stack>>>
3fff0b10:  00000000 00000000 3fff30ec 4020ab71  
3fff0b20:  4e202d2d 53205054 65767265 6f682072  
3fff0b30:  616e7473 203a656d 6c6f6f70 70746e2e  
3fff0b40:  67726f2e 40000a0d 3fff0ad8 00000008  
3fff0b50:  3fff0ad8 00000018 3fff0b98 4020c348  
3fff0b60:  3fff0ba0 3fff0b70 00000008 00000019  
3fff0b70:  3fff0ad8 00000008 3fff37e4 00000004  
...
3fff4c10:  00000000 00000000 00000000 00000000  
3fff4c20:  00000000 00000000 00000000 00000000  
3fff4c30:  00000000 00000000 00000000 00000000  
3fff4c40:  00000000 00000000 00000000 00000000  
3fff4c50:  00000000 00000000 00000000 00000000  
3fff4c60:  00000000 00000000 00000000 00000000  
3fff4c70:  00000000 00000000 00000000 00000000  
3fff4c80:  00000000 000000⸮
 ets Jan  8 2013,rst cause:4, boot mode:(1,6)

wdt reset