src: fix may be uninitialized warning in n-api

PR-URL: #21898
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: Jon Moss <me@jonathanmoss.me>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

src/node_api.cc

@@ -3849,7 +3849,7 @@ class TsFn: public node::AsyncResource {
   }
 
   void DispatchOne() {
-    void* data;
+    void* data = nullptr;
     bool popped_value = false;
     bool idle_stop_failed = false;