check_systemd_service: make sure the service exists

check_systemd_service.sh

@@ -41,6 +41,12 @@ if [ -z "$UNIT_NAME" ]; then
   exit -1
 fi
 
+# Check if the unit exists
+if ! systemctl list-units --full -all | grep -Fq "\b$UNIT_NAME.service\b"; then
+    echo "CRITICAL - $UNIT_NAME does not exist"
+    exit 2
+fi
+
 # Check if the unit is enabled
 enabled=$(systemctl is-enabled "$UNIT_NAME")
 if [ "$enabled" != "enabled" ] && [ "$IS_ALLOWED_DISABLED" = false ]; then