Hello @Rehan_Ahmed,
Thanks a lot about getting back to me. Unfortunately I do not have access to your notebook. I see that you have created a new issue on Discourse about the same issue. As I was not able to replicate the error that you were receiving, this seems like it is an internal error with the notebook.
I know that @Mubsi has internal reach to notebooks. I want to tag him on my response for your issue to be resolved.
You do not have to worry about the deadline of your assignment/lab as the date you complete your assignment does not contribute to your passing grade. Coursera platform automatically renews the deadlines.
I just read the community forum and other posts:
I saw some several hints provided by other learners who shared how they fixed this problem. Maybe their hints can be helpful to you.
Once again, thanks a lot for asking questions and making use of the Discourse Community.
Regards,
Can Koz