When I install my module, I get the following error:
Declaration of Drupal\media_gallery\Form\GalleryForm::create() must be compatible with Drupal\Core\DependencyInjection\ContainerInjectionInterface::create(Symfony\Component\DependencyInjection\ContainerInterface $container) in
I can't uninstall my module and I need to re-install all Drupal 8, since my module is not displayed in the uninstall tab.
How can I fix this without re-installing Drupal 8?
I'm not sure what exactly you are asking?
Yes, I've seen it as well that when a module installation fails, then it is neither installed nor uninstalled properly. That seems like a core bug, not something that can be "answered away", so you should open a bug report instead.
For the actual error you have, the only thing that is not already in the message is that you might be missing the user for ContainerInterface or have the wrong use.
I believe that Drush has the ability to uninstall modules.
