I am trying to use the PLV8 via function and while using the function created via PLV8 in one of the create materialized view, postgres crashes, attached is the log file with DEBUG5 turned on.
These are not the correct place to post possible bug reports for third-party extensions. plV8 has an active Issues listing on GitHub and you should post your observations there. They can report upstream to us if there is indeed something specific in core causing their code to fail.
Additionally, in the future if you find that your email is indeed a core PostgreSQL issue please just submit it to one of the available lists. If you are unsure pgsql-general is a safe choice. For this email enough information has been provided that our official pgsql-bugs email list (or form) would be acceptable and indeed preferred.