Yesterday I was wondering if it was not good to make an improvement to the alias, to return null or empty if it does not exist, to accept only string, to improve it at least to try to avoid the smallest possible errors.
When I test assets implement one with FS, and the truth eliminate all aliases, flysystem does not care if you use the memory adapter, or the S3 adapter, or the local /src/assets and /public/web will always be the same.