Zero-byte allocation causes assertion failure

[tniessen]

• Version: 11.6.0
• Platform: Ubuntu, Windows
• Subsystem: crypto

Passing an empty string to any function that parses a private key causes an assertion failure:

> crypto.createPrivateKey({ key: '' })
C:\WINDOWS\system32\cmd.exe - node[12104]: src\node_crypto.cc:2675: Assertion `(mem) != nullptr' failed.

[juanarbol]

Same in macOS high sierra

[ryzokuken]

@tniessen are you looking into this or should I give it a swing?

P.S. should've seen the ref.

[cjihrig]

#25248