fix: handle repos with no tags

Author: andhreljaKern

dc/registry_delete.sh

@@ -41,7 +41,12 @@ function validate_image_tag() {
 # Delete images older than DELETE_SINCE_DAYS and exit 0
 if [ -n "$DELETE_SINCE_DAYS" ]; then
     echo "::notice::Deleting images older than $DELETE_SINCE_DAYS days"
-    repo_tags=$(curl -s -u $HTTPS_USERNAME https://$REGISTRY_URL/v2/$GITHUB_OWNER/$APP_NAME/tags/list | jq -r '.tags[]')
+    repo_tags=$(curl -s -u $HTTPS_USERNAME https://$REGISTRY_URL/v2/$GITHUB_OWNER/$APP_NAME/tags/list | jq -r '.tags[]?')
+    if [ -z "$repo_tags" ]; then
+        echo "::warning::No images found for $APP_NAME"
+        exit 0
+    fi
+    
     while IFS= read -r tag; do
         manifest=$(curl -s -u $HTTPS_USERNAME \
             -H "Accept: application/vnd.docker.distribution.manifest.v2+json" \