crypto: simplify KeyObject constructor

Inline a function that only gets called in the constructor. Make call to
`super()` more straightforward in the process by removing conditional
involving the function as it only ever returns `undefined` or else
throws. That made the code a little hard to understand, as without
looking at the function, one would likely expect it to return `true`
on success rather than `undefined`.

PR-URL: #35064
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Denys Otrishko <shishugi@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>

lib/internal/crypto/keys.js

@@ -43,13 +43,6 @@ for (const m of [[kKeyEncodingPKCS1, 'pkcs1'], [kKeyEncodingPKCS8, 'pkcs8'],
                  [kKeyEncodingSPKI, 'spki'], [kKeyEncodingSEC1, 'sec1']])
   encodingNames[m[0]] = m[1];
 
-function checkKeyTypeAndHandle(type, handle) {
-  if (type !== 'secret' && type !== 'public' && type !== 'private')
-    throw new ERR_INVALID_ARG_VALUE('type', type);
-  if (typeof handle !== 'object' || !(handle instanceof KeyObjectHandle))
-    throw new ERR_INVALID_ARG_TYPE('handle', 'object', handle);
-}
-
 // Creating the KeyObject class is a little complicated due to inheritance
 // and that fact that KeyObjects should be transferrable between threads,
 // which requires the KeyObject base class to be implemented in C++.
@@ -64,7 +57,12 @@ const [
   // Publicly visible KeyObject class.
   class KeyObject extends NativeKeyObject {
     constructor(type, handle) {
-      super(checkKeyTypeAndHandle(type, handle) || handle);
+      if (type !== 'secret' && type !== 'public' && type !== 'private')
+        throw new ERR_INVALID_ARG_VALUE('type', type);
+      if (typeof handle !== 'object' || !(handle instanceof KeyObjectHandle))
+        throw new ERR_INVALID_ARG_TYPE('handle', 'object', handle);
+
+      super(handle);
 
       this[kKeyType] = type;