crypto: simplify error handling in ECDH::New

The type of the argument is being checked within JS which makes the
type checking in C++ unnecessary.

PR-URL: #23647
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>

Author: tniessen

src/node_crypto.cc

@@ -4342,7 +4342,7 @@ void ECDH::New(const FunctionCallbackInfo<Value>& args) {
   MarkPopErrorOnReturn mark_pop_error_on_return;
 
   // TODO(indutny): Support raw curves?
-  THROW_AND_RETURN_IF_NOT_STRING(env, args[0], "ECDH curve name");
+  CHECK(args[0]->IsString());
   node::Utf8Value curve(env->isolate(), args[0]);
 
   int nid = OBJ_sn2nid(*curve);