Twig extension issues
Your module name should not be camel case, but should instead be mymodule (not MenuRender). Your namespace needs to reflect that, too. It should likely live under a folder in src called TwigExtension, and your module name in the namespace should match the directory (i.e. Drupal\mymodule, not Drupal\MyModule).

Here is a module that uses TwigExtension for comparison.

What's likely happening is the application is unable to locate certain things due to the file naming and namespacing.