Callback invoked twice on unhandled exception

[adamjmcgrath]

The callback handler is invoked twice when there is an unhandled exception in the callback, eg:

const { SignedXml } = require("xml-crypto");
const crypto = require("crypto");

const xml = `<x xmlns:wsu='http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd' Id='_1'></x>`;
const sig = new SignedXml();
sig.privateKey = crypto.generateKeyPairSync("rsa", {
  modulusLength: 2048,
  privateKeyEncoding: {
    type: "pkcs1",
    format: "pem"
  }
}).privateKey;
sig.canonicalizationAlgorithm = "http://www.w3.org/2001/10/xml-exc-c14n#";
sig.signatureAlgorithm = "http://www.w3.org/2000/09/xmldsig#rsa-sha1";
sig.computeSignature(xml, (err, result) => {
  console.log("Callback invoked", !!err, !!result);
  throw new Error('Error Thrown');
});

// Results in:
// Callback invoked false true
// Callback invoked true false

// Error: Error Thrown

The callback should only be invoked a single time, eg:

require('fs').readdir(".", (err, files) => {
  console.log("Callback invoked", !!err, !!files);
  throw new Error('Error Thrown');
});

// Results in:
// Callback invoked false true

// Error: Error Thrown

I believe the problem is the synchronous execution of the callback in https://github.com/node-saml/xml-crypto/blob/master/src/types.ts#L259

[srd90]

I believe the problem is the synchronous execution of the callback in https://github.com/node-saml/xml-crypto/blob/master/src/types.ts#L259

That link becomes obselete once someone modifies types.ts at master branch so that there shall be new lines of code on top of line 259

Here is link to that line so that link is pinned to same version of types.ts that was most recent version of master branch when this issue was created:

xml-crypto/src/types.ts

Line 259 in b673581

possibleCallback(null, result);