Hello,
I haven't tested it with xdebug enabled, my bad. In my local environment it works as expected.
Since you are using xdebug, can you set a breakpoint for this specific line? It should highlight it's value.
Otherwise, can you try and remove that die? Just have it as: print_r($this->context->link->getModuleLink('lebruntwofa', 'sendcode'));
If you go to the module manager page, it should display the link on top of the page.
You can also try and access: <base_url>/en/module/lebruntwofa/sendcode - as this is most likely the URL (or /fr/ instead of the /en/)
Let me know if this works