I think that in the file Stores/KeyStore.php the line:
yield File\changeOwner($file, 0600);
should be:
yield File\changePermissions($file, 0600);
Using the value "0600" does not make any sense for changeOwner, as the value should be a user ID in that case. "0600" looks like a file permission in octal format.
You can see clearly in the following modification from about a month ago, it was incorrectly changed:
From chmod to changeOwner... Which is incorrect obviously.