With the new handler:

wifi_event_sta_disconnected_t* event = (wifi_event_sta_disconnected_t*) event_data;

if(WIFI_REASON_4WAY_HANDSHAKE_TIMEOUT == event->reason || WIFI_REASON_AUTH_FAIL == event->reason)
{
g_fatal_error = true;
ESP_LOGI(TAG,"Incorrect WiFi Credentials");
}

I've got it figured out. Thanks

wifi_event_sta_disconnected_t* event = (wifi_event_sta_disconnected_t*) event_data;
ESP_LOGI(TAG, "%d", event->reason);

How do I get the reason code with the non legacy event loop?
ie: static void event_handler(void* arg, esp_event_base_t event_base, int32_t event_id, void* event_data)

I understand with the legacy eventloop:
esp_err_t event_handler(void *ctx, system_event_t *event)

I can get the info:
system_event ...