The docker logs command will show you the output a container is generating when you don’t run it interactively. This is likely to include the error message.
docker logs --tail 50 --follow --timestamps mediawiki_web_1
You can also run a fresh container in the foreground with docker run -ti <your_wiki_image> to see what that does. You may need to map some config from your docker-compose yml to the docker command.
I would guess that attaching to the media wiki process caused a crash which has corrupted something in your data.