netdata: survive a failed apt update, leave quietly on Cancel

The add-on runs on the Proxmox host, where the enterprise repository without a
subscription answers 401 and apt update exits 100 (2 of 3 failures in three
days). apt_update_safe retries, points at the enterprise repository and
carries on; the netdata repository was fetched fine.

Cancel in the first menu was reported as a failed run.

ct/technitiumdns.sh

@@ -47,7 +47,7 @@ function update_script() {
     $STD apt install -y aspnetcore-runtime-10.0
   fi
 
-  RELEASE=$(get_latest_github_release "TechnitiumSoftware/DnsServer")
+  RELEASE=$(curl -fsSL https://technitium.com/dns/ | grep -oP 'Version \K[\d.]+')
   if [[ ! -f ~/.technitium || ${RELEASE} != "$(cat ~/.technitium 2>/dev/null)" ]]; then
     fetch_and_deploy_from_url "https://download.technitium.com/dns/DnsServerPortable.tar.gz" /opt/technitium/dns
     echo "${RELEASE}" >~/.technitium

install/technitiumdns-install.sh

@@ -23,7 +23,7 @@ setup_deb822_repo \
 $STD apt install -y aspnetcore-runtime-10.0
 msg_ok "Installed Dependencies"
 
-RELEASE=$(get_latest_github_release "TechnitiumSoftware/DnsServer")
+RELEASE=$(curl -fsSL https://technitium.com/dns/ | grep -oP 'Version \K[\d.]+')
 fetch_and_deploy_from_url "https://download.technitium.com/dns/DnsServerPortable.tar.gz" /opt/technitium/dns
 echo "${RELEASE}" >~/.technitium
 

tools/addon/netdata.sh

@@ -80,7 +80,7 @@ install() {
   msg_ok "Set up repository"
 
   msg_info "Installing ${APP}"
-  $STD apt update
+  apt_update_safe
   $STD apt install -y netdata
   msg_ok "Installed ${APP}"
   msg_ok "Completed successfully!\n"
@@ -108,7 +108,7 @@ OPTIONS=(Install "Install ${APP} on Proxmox VE"
   Uninstall "Uninstall ${APP} from Proxmox VE")
 
 CHOICE=$(whiptail --backtitle "Proxmox VE Helper Scripts" --title "${APP}" \
-  --menu "Select an option:" 10 58 2 "${OPTIONS[@]}" 3>&1 1>&2 2>&3)
+  --menu "Select an option:" 10 58 2 "${OPTIONS[@]}" 3>&1 1>&2 2>&3) || exit 0
 
 case $CHOICE in
 "Install") install ;;