multiple execution when using ifelse

my code:
    s<-function(v,k){
      ifelse(k>length(v),print("error,k>length(v)"),return(v-k))
    }
    v=1:5
    k=6
    s(v,k)

output:

> s(v,k)
[1] "error,k>length(v)"
[1] "error,k>length(v)"

1. 
   

   Why is this printing twice? thanks

   
   


2. 
   

   Is there some kind of error handler I could use here?