Add failing with an error if inventory parts not found in the library

tests/inventory.sh

@@ -45,4 +45,10 @@ for ITEM in ${ITEMS}; do
   fi
 done
 
-echo "Total errors: ${ERRORS}"
+if [ ${ERRORS} -eq 0 ]; then
+  echo -e "${GREEN}SUCCESS: All parts can be found!${RESET}"
+  exit 0
+else
+  echo -e "${RED}ERROR(${ERRORS}): Some parts could not be found.${RESET}"
+  exit 1
+fi