Update install.sh

install.sh

@@ -26,6 +26,7 @@ if [ $( grep -c '^stretch$\|^buster$' <<< $codename ) == 0 ]; then
   echo "ERROR: Sorry, this script doesn't recognise your Debian version."
   echo "  You may need to install lsb_release, or check your version."
   echo "  Expected 'stretch' or 'buster' but got '$codename'."
+  exit 1
 fi
 
 if ! hostname --fqdn > /dev/null 2>&1 ; then
@@ -33,7 +34,7 @@ if ! hostname --fqdn > /dev/null 2>&1 ; then
   echo "  You should check it has a matching enty in /etc/hosts and is"
   echo "  set properly before continuing, as Sympl uses the hostname."
   echo "  You can check it's current setting with 'hostname -f'."
-  exit 0
+  exit 1
 fi
 
 echo "Installing Sympl from '$version' repository."