Fix process crash (!) when no certificate is present (can be considered a vulnerability)

[nikitaeverywhere]

It can be that the certificate is just not returned by the server for https connections (port 443):

The weirdest part is, it crashes the entire NodeJS process when using your package, i.e. all programs using this package are vulnerable:

...\node_modules\ssl-checker\lib\cmjs\index.js:59
                    validFrom: new Date(valid_from).toISOString(),
                                                    ^

RangeError: Invalid time value
    at Date.toISOString (<anonymous>)
    at ClientRequest.<anonymous> (...\node_modules\ssl-checker\lib\cmjs\index.js:59:53)
    at Object.onceWrapper (events.js:421:26)
    at ClientRequest.emit (events.js:314:20)
    at HTTPParser.parserOnIncomingClient [as onIncoming] (_http_client.js:640:27)
    at HTTPParser.parserOnHeadersComplete (_http_common.js:119:17)
    at TLSSocket.socketOnData (_http_client.js:509:22)
    at TLSSocket.emit (events.js:314:20)
    at addChunk (_stream_readable.js:303:12)
    at readableAddChunk (_stream_readable.js:279:9)
Exit status 1

$ node -v
v14.9.0

The above error is a process-level error, and there is no way to catch it (but only globally). I suspect NodeJS is also not handling errors in the https.request callback correctly, but I can't invest too much time to investigate it, rather I am suggesting a quick fix. The root cause of the problem is .getPeerCertificate() returning {}. I also didn't find any suitable domain at https://badssl.com to write the test which reproduces it, but you can reproduce it easily by adding a throw new Error('whatever') inside the https.request's callback.

Thanks for a great package! Looking forward to seeing this fix on npm.

P.S. If you want this PR to count towards my Hacktoberfest contributions, please add a hacktoberfest-accepted label to it. Thanks!

[nikitaeverywhere]

Thanks! Any chance for adding a hacktoberfest-accepted label? 😇

[nikitaeverywhere]

I mean this:

Thanks in advance!