Close unused connection using lapply in R

Question

I'm excecuting the following code in R:

dados <- lapply(lista_prop_final, function(x){tryCatch(do.call(cham_votes, x),
                                                   error=function(e){NA})})

In which lista_prop_final is a list of lists of three character objects (type, number and year). The code runs fine, but I'm receiving a series of messages like this one when the execution ends:

1: closing unused connection 3 (http://www.camara.leg.br/SitCamaraWS/Proposicoes.asmx/ObterVotacaoProposicao?tipo=PL&numero=4904&ano=1995)

It looks like those URLs are the ones in which the function returns an error (that's why I'm using tryCatch ).

Do you know how to solve these warning messages?

Thanks for your help!

Obs.: the cham_votes function is from the congressbr package.