It’s a bit premature to declare this to be a bug in Terraform. There are local reasons that could have corrupted the module directory or its contents.
There’s a lot of investigation you could do to identify the problem, but if this is the first time you’ve seen this problem it’s often more effective to reset & retry:
Remove the .terraform directory tree. Don’t do this if you’ve manually put special things in your .terraaform directory tree like your tfstate file.
cd to root module’s directory
rm -r .terraform
Do a fresh “terraform init”
This will create a fresh copy of the module directory on your local system.
Note that public modules like terraform-aws-modules are not officially maintained by HashiCorp.