Hard crash in generateKeyPair on bad `type`

[ChALkeR]

@deepview-autofix flag:

To reproduce:

require('crypto').generateKeyPair('toString', {}, console.log)

require('crypto').generateKeyPairSync('toString')

type is unlikely to be attacker-controlled without validation on the application side, so I don't think this is worth a private report and does not qualify as a vuln (also, DoS at most)

But should still be fixed