Paddle API key is not configured
paddle-api threw because the API key is empty before calling Paddle.
Why this happens
Checkout toggle may be on without pasting the key. Sibling of broader “checkout is not configured/enabled” messages.
Diagnose and fix
1. Admin → Settings → Payment → Paddle — paste API key; save.
2. Enable Paddle checkout; set webhook secret if required.
3. Match sandbox vs live keys to the mode you intend.
4. See Paddle.