feature request ctid cast / sql exception

Hello,

this is a feature request for a rather simple functionality.

I propose to implement a builtin and efficient bidirectional cast between
ctid and bigint types.

Another nice feature would be a function that can be called from a sql
statement and would throw an exception when executed.

I know these functions can be implemented using UDF, but the performance
and need to deploy it to every database is very inconvenient.

Thank you