Errors

Check the HTTP status first. For 422, read data[]. Otherwise use message.

{
  "message": "Customer not found",
  "data": null
}

{
  "message": "Invalid email address",
  "data": [
    { "path": "email", "message": "Invalid email address", "location": "body" }
  ]
}

Status	Meaning
`400`	Business rule
`401`	Bad or missing key
`403`	IP not whitelisted
`404`	Not found
`409`	Conflict
`422`	Schema validation (`data` is an issues array)
`429`	Rate limit (100 req / 15 min per IP)
`500`	Server error

429 is { status, message } — not the usual envelope. Back off and retry.