What is vkEnumerateInstanceExtensionProperties failed -6 about ncnndotnet HOT 7 CLOSED

static void AppGetGlobalLayerExtensions(char *layer_name, uint32_t *extension_count, VkExtensionProperties **extension_properties) {
    VkResult err;
    uint32_t ext_count = 0;
    VkExtensionProperties *ext_ptr = NULL;

    /* repeat get until VK_INCOMPLETE goes away */
    do {
        // gets the extension count if the last parameter is NULL
        err = vkEnumerateInstanceExtensionProperties(layer_name, &ext_count, NULL);
        assert(!err);

        if (ext_ptr) {
            free(ext_ptr);
        }
        ext_ptr = malloc(ext_count * sizeof(VkExtensionProperties));
        // gets the extension properties if the last parameter is not NULL
        err = vkEnumerateInstanceExtensionProperties(layer_name, &ext_count, ext_ptr);
    } while (err == VK_INCOMPLETE);
    assert(!err);
    *extension_count = ext_count;
    *extension_properties = ext_ptr;
}
```