Fix mismatches for apparent methods not registered

[DyfanJones]

Mismatches for apparent methods not registered:
as.list:
function(x, ...)
as.list.struct:
function(x)
See section 'Registering S3 methods' in the 'Writing R Extensions'

https://win-builder.r-project.org/incoming_pretest/paws.common_0.5.7_20230624_181359/Windows/00check.log