Adding a User ID with a bare email address should emit a warning
Consider:
$ sq key generate -u 'alice@example.com' --export /tmp/alice.pgp
$ echo $?
0
This should emit a warning along the lines of: "To create a User ID with a bare email address, you should surround it with angle brackets, like so: alice@example.com".
This has to do with how email addresses are matched against the standard regular expression used in tsigs: https://gitlab.com/sequoia-pgp/sequoia/-/blob/31b380c7/openpgp/src/regex/mod.rs#L78