add build

dist/lib/index.js

@@ -10,7 +10,8 @@ const verifyPDF = (pdf) => {
         (0, generalUtils_1.checkForSubFilter)(pdfBuffer);
     }
     catch (error) {
-        throw new Error(error.message);
+        //SubFilter is only available if there is a sig in the pdf
+        return null;
     }
     try {
         const { signatureStr, signedData, signatureMeta } = (0, signatureUtils_1.extractSignature)(pdfBuffer);