Remove image preload refs without href

src/asset-inliner.mjs

@@ -206,11 +206,11 @@ export class AssetInliner {
     const rel = getAttribute(tag, "rel") || "";
     const href = getAttribute(tag, "href");
     const asValue = getAttribute(tag, "as") || "";
-    if (!href) {
-      return tag;
-    }
 
     if (/\bstylesheet\b/i.test(rel)) {
+      if (!href) {
+        return tag;
+      }
       const absolute = resolveUrl(href, baseUrl);
       if (!absolute || absolute.startsWith("data:")) {
         return "";
@@ -237,12 +237,19 @@ export class AssetInliner {
     }
     let output = tag;
     if (/\bpreload\b/i.test(rel) && /^image$/i.test(asValue)) {
+      if (!href) {
+        return "";
+      }
       const imageSrcset = getAttribute(output, "imagesrcset");
       if (imageSrcset) {
         output = setAttribute(output, "imagesrcset", await this.inlineSrcset(imageSrcset, baseUrl));
       }
     }
 
+    if (!href) {
+      return tag;
+    }
+
     const dataUri = await this.toDataUri(href, baseUrl, linkResourceType(asValue));
     if (!dataUri) {
       return "";