I have been working as Team Lead, Engineering Manager, CTO etc some times I got praise, and other times biting criticism, both are important for growth. What matters after getting your job well done done is this:
I’m sad to see you go but I don’t blame you at all! I just wanted to let you know that I enjoyed working with you and that I’m thankful that you introduced me to so many new technologies. I feel that I’ve learned a lot in the time you’ve been here and have grown as a developer. I wish you luck for the future and hope your next job is better than this one.