Only try to remove parts inthe file if the file already exists

automated install/basic-install.sh

@@ -873,7 +873,9 @@ configureFirewall() {
 
 finalExports() {
 	# Update variables in setupVars.conf file
-	sed -i.update.bak '/PIHOLE_DOMAIN/d;/IPV4_ADDRESS/d;/IPV6_ADDRESS/d;/PIHOLE_DNS_1/d;/PIHOLE_DNS_2/d;/QUERY_LOGGING/d;' "${setupVars}"
+	if [ -e "${setupVars}" ]; then
+		sed -i.update.bak '/PIHOLE_DOMAIN/d;/IPV4_ADDRESS/d;/IPV6_ADDRESS/d;/PIHOLE_DNS_1/d;/PIHOLE_DNS_2/d;/QUERY_LOGGING/d;' "${setupVars}"
+	fi
     {
 	echo "PIHOLE_INTERFACE=${PIHOLE_INTERFACE}"
 	echo "IPV4_ADDRESS=${IPV4_ADDRESS}"