async_hooks: use CHECK instead of throwing error

SetupHooks is only available via `process.binding('async_wrap')`, so
there's no reason it shouldn't be called with the appropriate arguments,
since it is an internal-only function. The only place this function is
used is `lib/internal/async_hooks.js`.

PR-URL: #17832
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Anatoli Papirovski <apapirovski@mac.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

src/async_wrap.cc

@@ -343,8 +343,7 @@ static void PromiseHook(PromiseHookType type, Local<Promise> promise,
 static void SetupHooks(const FunctionCallbackInfo<Value>& args) {
   Environment* env = Environment::GetCurrent(args);
 
-  if (!args[0]->IsObject())
-    return env->ThrowTypeError("first argument must be an object");
+  CHECK(args[0]->IsObject());
 
   // All of init, before, after, destroy are supplied by async_hooks
   // internally, so this should every only be called once. At which time all