While the Git gc command optimizes and removes dead objects from the repo, the fsck command reports on repo problems.
git fsck
I used to run it with the –full option, but this is now the default. I typically run it as is or with the –tags option. You may occasionally appreciate the –strict and –verbose options as well.
Note – it is not a repair tool. It will report any missing or corrupted data/git objects, but not repair them. Your backups, central repo, or teammates’ repos are your recovery options.