n-api: Retain last code when getting error info

Unlike most N-API functions, `napi_get_last_error_info()` should not
clear the last error code when successful, because a pointer to (not
a copy of) the error info structure is returned via an out parameter.

PR-URL: https://github.com/nodejs/node/pull/13087
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>

src/node_api.cc

@@ -755,7 +755,7 @@ napi_status napi_get_last_error_info(napi_env env,
       error_messages[env->last_error.error_code];
 
   *result = &(env->last_error);
-  return napi_clear_last_error(env);
+  return napi_ok;
 }
 
 napi_status napi_create_function(napi_env env,

test/addons-napi/test_napi_status/test_napi_status.cc

@@ -10,6 +10,14 @@ napi_value createNapiError(napi_env env, napi_callback_info info) {
 
   NAPI_ASSERT(env, status != napi_ok, "Failed to produce error condition");
 
+  const napi_extended_error_info *error_info = 0;
+  NAPI_CALL(env, napi_get_last_error_info(env, &error_info));
+
+  NAPI_ASSERT(env, error_info->error_code == status,
+    "Last error info code should match last status");
+  NAPI_ASSERT(env, error_info->error_message,
+    "Last error info message should not be null");
+
   return nullptr;
 }