“Exception has occurred” when debugging arduino uno using avr-debug library

Hi, I find that there is an excellent library, avr-debug, which made by Jan Dolinay. Thanks to Jan Dolinay.

Following the instructions in the “doc/avr_debug.pdf”,I debug arduino uno successfully in vscode.

But there is a minor flaws, as the picture illustrated in the attachment. Everytime the “debug arrow” returns to the loop() function from main(), an unexpected message appears, it says “Exception has occurred. Unknow stopping event”.
Although this message doesn’t affect the debugging process, I don’t know why it appears.

Does anyone encounter the similar case? And why it appears?
Best regards.