Don't add cert if letsencrypt complains

It makes no sense to call uberspace-add-certificate if letsencrypt
fails

letsencrypt-renew.sh

@@ -52,7 +52,7 @@ for inifile in "${LECONFIGDIR}"/cli-*.ini; do
 	openssl x509 -checkend $(( 21 * 86400 )) -in "${LECONFIGDIR}/live/${domain}/cert.pem" > /dev/null && continue
 
 	# run let's encrypt
-	letsencrypt certonly -c "${inifile}"
+	letsencrypt certonly -c "${inifile}" || continue
 
 	# import certificate
 	uberspace-add-certificate -k "${LECONFIGDIR}/live/${domain}/privkey.pem" -c "${LECONFIGDIR}/live/${domain}/cert.pem"