Enforce ZIP 64

src/lib/check-dduf.ts

@@ -101,7 +101,9 @@ export async function* checkDduf(
 		fileCount = Number(view.getBigUint64(index + 32, true));
 
 		opts?.log?.('File count zip 64: ' + fileCount);
-	}
+	} else {
+      throw new Error("DDUF files need to be in zip 64 format!")
+    }
 
 	opts?.log?.('Central directory size: ' + centralDirSize);
 	opts?.log?.('Central directory offset: ' + centralDirOffset);