crypto: move _pbkdf2 call out of handleError funct

This commit moves the _pbkdf2 function call out of the handleError
function, which now only takes in an error and a digest object as
its parameters.

lib/internal/crypto/pbkdf2.js

@@ -38,14 +38,15 @@ function pbkdf2(password, salt, iterations, keylen, digest, callback) {
     callback.call(wrap, null, keybuf.toString(encoding));
   };
 
-  handleError(keybuf, password, salt, iterations, digest, wrap);
+  handleError(_pbkdf2(keybuf, password, salt, iterations, digest, wrap),
+              digest);
 }
 
 function pbkdf2Sync(password, salt, iterations, keylen, digest) {
   ({ password, salt, iterations, keylen, digest } =
     check(password, salt, iterations, keylen, digest));
   const keybuf = Buffer.alloc(keylen);
-  handleError(keybuf, password, salt, iterations, digest);
+  handleError(_pbkdf2(keybuf, password, salt, iterations, digest), digest);
   const encoding = getDefaultEncoding();
   if (encoding === 'buffer') return keybuf;
   return keybuf.toString(encoding);
@@ -71,9 +72,7 @@ function check(password, salt, iterations, keylen, digest) {
   return { password, salt, iterations, keylen, digest };
 }
 
-function handleError(keybuf, password, salt, iterations, digest, wrap) {
-  const rc = _pbkdf2(keybuf, password, salt, iterations, digest, wrap);
-
+function handleError(rc, digest) {
   if (rc === -1)
     throw new ERR_CRYPTO_INVALID_DIGEST(digest);