crypto: move _scrypt call out of handleError funct

This commit moves the _scrypt function call out of the handleError
function, which now only takes in an error object as its parameter.

The motivation for this is to hopefully improve readability as it was
not clear to me the first time I stepped through the code where the
actual call to _scrypt was.

PR-URL: #28318
Reviewed-By: Yongsheng Zhang <zyszys98@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: James M Snell <jasnell@gmail.com>

lib/internal/crypto/scrypt.js

@@ -44,23 +44,21 @@ function scrypt(password, salt, keylen, options, callback = defaults) {
     callback.call(wrap, null, keybuf.toString(encoding));
   };
 
-  handleError(keybuf, password, salt, N, r, p, maxmem, wrap);
+  handleError(_scrypt(keybuf, password, salt, N, r, p, maxmem, wrap));
 }
 
 function scryptSync(password, salt, keylen, options = defaults) {
   options = check(password, salt, keylen, options);
   const { N, r, p, maxmem } = options;
   ({ password, salt, keylen } = options);
   const keybuf = Buffer.alloc(keylen);
-  handleError(keybuf, password, salt, N, r, p, maxmem);
+  handleError(_scrypt(keybuf, password, salt, N, r, p, maxmem));
   const encoding = getDefaultEncoding();
   if (encoding === 'buffer') return keybuf;
   return keybuf.toString(encoding);
 }
 
-function handleError(keybuf, password, salt, N, r, p, maxmem, wrap) {
-  const ex = _scrypt(keybuf, password, salt, N, r, p, maxmem, wrap);
-
+function handleError(ex) {
   if (ex === undefined)
     return;