Rst:0x8 (TG1WDT_SYS_RESET)

Hello.
In the code, when the cb method of the uart dispatcher is called and processed, the device is rebooted with the output of the following information:
rst:0x8 (TG1WDT_SYS_RESET),boot:0x12 (SPI_FAST_FLASH_BOOT)

May be someone met such problem?
What could it be?

UPD:
After the first reboot by TG1WDT_SYS_RESET, the problem doesn’t appear.