[plt-scheme] Question about map

Hi All,

I am using v4.0.1.

This code: (map caadr localdefs)

Produces this error:

mcar: expects argument of type <mutable-pair>; given #<undefined>

My code does not use mcar anywhere. I must assume it has to do with
the implementation of map (?).

Any pointers much appreciated.

Cheers,

Marco