src: do not crash if ToggleAsyncHook fails during termination

In the termination case, we should not crash. There’s also no harm
being done by ignoring the termination exception here, since the
thread is about to be torn down anyway.

Also, add a guard against running this during shutdown. That is the
likely cause of #34361.

Fixes: #34361

PR-URL: #34362
Fixes: #27261
Reviewed-By: Gus Caplan <me@gus.host>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

Author: addaleax

src/inspector_agent.cc

@@ -841,13 +841,18 @@ void Agent::DisableAsyncHook() {
 
 void Agent::ToggleAsyncHook(Isolate* isolate,
                             const Global<Function>& fn) {
+  // Guard against running this during cleanup -- no async events will be
+  // emitted anyway at that point anymore, and calling into JS is not possible.
+  // This should probably not be something we're attempting in the first place,
+  // Refs: https://github.com/nodejs/node/pull/34362#discussion_r456006039
+  if (!parent_env_->can_call_into_js()) return;
   CHECK(parent_env_->has_run_bootstrapping_code());
   HandleScope handle_scope(isolate);
   CHECK(!fn.IsEmpty());
   auto context = parent_env_->context();
   v8::TryCatch try_catch(isolate);
   USE(fn.Get(isolate)->Call(context, Undefined(isolate), 0, nullptr));
-  if (try_catch.HasCaught()) {
+  if (try_catch.HasCaught() && !try_catch.HasTerminated()) {
     PrintCaughtException(isolate, context, try_catch);
     FatalError("\nnode::inspector::Agent::ToggleAsyncHook",
                "Cannot toggle Inspector's AsyncHook, please report this.");