test check unexisting variable

functions/command_fastdl.sh

@@ -90,7 +90,7 @@ fn_scriptlog "Configuration"
 sleep 2
 echo -en "\n"
 # Prompt for clearing old files if folder was already here
-if [ ${newfastdl} == 0 ]; then
+if [ -z "${newfastdl}" ] && [ "${newfastdl}" == "0" ]; then
 	fn_printdots
 	while true; do
 		read -e -i "y" -p "Clear old FastDL files? [Y/n]" yn