Why is .pfx file mandatory while e sign? I am trying to use https://github.com/aspose-pdf-cloud/aspose-pdf-cloud-node.js/blob/master/test/testFields.ts#L307 to understand how e sign can be implemen......“Message”: “Object reference not set to an instance of an object.”, “Description”:...PostSignatureField - Object reference not set to an instance of an object. Read...