src: fix crash on FSReqPromise destructor

We are deciding whether to end `fs` promises by checking
`can_call_into_js()` whereas in the `FSReqPromise` destructor we're
using the `is_stopping()` check. Though this may look as semantically
correct it has issues because though both values are modified before
termination on `Environment::ExitEnv()` and both are atomic they are not
syncronized together so it may happen that when reaching the destructor
`call_into_js` may be set to `false` whereas `is_stopping` remains
`false` causing the crash. Fix this by using the same checks everywhere.

Fixes: nodejs#43499

src/node_file.cc

@@ -377,7 +377,7 @@ MaybeLocal<Promise> FileHandle::ClosePromise() {
     std::unique_ptr<CloseReq> close(CloseReq::from_req(req));
     CHECK_NOT_NULL(close);
     close->file_handle()->AfterClose();
-    if (!close->env()->can_call_into_js()) return;
+    if (close->env()->is_stopping()) return;
     Isolate* isolate = close->env()->isolate();
     if (req->result < 0) {
       HandleScope handle_scope(isolate);
@@ -651,7 +651,7 @@ void FSReqAfterScope::Reject(uv_fs_t* req) {
 }
 
 bool FSReqAfterScope::Proceed() {
-  if (!wrap_->env()->can_call_into_js()) {
+  if (wrap_->env()->is_stopping()) {
     return false;
   }