fix(scripts): exit when change log file is empty

.gitea/scripts/add-annotations.sh

@@ -100,7 +100,7 @@ done <<< "${COMMIT_TITLES}"
 if [ -s "${YAML_FILE}" ]; then
   yq --no-colors --inplace ".annotations.\"artifacthub.io/changes\" |= loadstr(\"${YAML_FILE}\") | sort_keys(.)" "${CHART_FILE}"
 else
-  echo "ERROR: Changelog file is empty: ${YAML_FILE}"
+  echo "ERROR: Changelog file is empty: ${YAML_FILE}" 1>&2
   exit 1
 fi