[fix] Avoid uninitialized variable
[fix] TYPEP(x,y) should check x is not null too
[fix] Avoid NULL dereference when trying to assign a filename dividing a relation
[fix] Remove useless assignment
[fix] If any of two LISP objects is NULL return NIL
[fix] Validate pos in add_fea_d to avoid out of bounds indexing
[fix] Avoid null pointer dereference
[fix] Avoid buffer overflow in wstrdup: if the string is too long then exit
[fix] Remove unused variables