There seems to be a problem with your garson-method in case of nnets with one hidden-unit:
set.seed(0);garson(nnet(data.frame(rnorm(100),rnorm(100)),rnorm(100),size=2)) #works
set.seed(0);garson(nnet(data.frame(rnorm(100),rnorm(100)),rnorm(100),size=1)) #does not work
There seems to be a problem with your garson-method in case of nnets with one hidden-unit:
set.seed(0);garson(nnet(data.frame(rnorm(100),rnorm(100)),rnorm(100),size=2)) #works set.seed(0);garson(nnet(data.frame(rnorm(100),rnorm(100)),rnorm(100),size=1)) #does not work