Is there a bug in this joke?

Original joke: There was once a joke: When Xiao Ming was one year old, he called grandpa for the first time, so grandpa died. Not long after he called his mother for the first time, she died. Later, he called Dad, and Carpenter Wang next door died. A doctor from Tsinghua University pointed out that there is a bug in this joke. When calling grandpa, it should be the father of Carpenter Wang next door who died. At this time, the mother of the carpenter next door said that this was not a bug... (Maybe this is not entirely the original joke, but it doesn't matter, the meaning is almost the same.)

Understanding: Xiao Ming's biological father is "the one next door." "Carpenter Wang"

Xiao Ming's biological grandfather is indeed this grandfather, not the father of "Carpenter Wang next door".

Since "the mother of the carpenter next door said that this was not a bug", it can be deduced that Xiao Ming's biological grandmother is actually the mother of "Carpenter Wang next door", because "Carpenter Wang next door" is Xiao Ming's biological child The child was born to his grandfather and his mother (Xiao Ming’s biological grandmother), the “Carpenter Wang next door”.

It’s a bit difficult to understand, so take your time. If you don’t understand, just ask again!

Please adopt if you are satisfied.