Cryptobot wrongly claims messages aren't encrypted if it can't decrypt them

I deliberately sent Cryptobot a message that was encrypted with a key that Cryptobot didn't have (intentionally using the wrong public key to encrypt).

I got back

You're not using PGP at all yet. Check out this guide to get get you started, [...]
WARNING: Your email was not signed. [...]
WARNING: Your email was encrypted, but I couldn't decrypt it. [...]
WARNING: You didn't include your public key. [...]

These messages actually contradict one another (the first message is wrong and contradicts the third; the second message is wrong but Cryptobot didn't actually know that; the fourth message is right but Cryptobot didn't actually know that).