Edge API returns 400 with no message if `allow_client_traits` is `false`

[rolodato]

How are you running Flagsmith

• Self Hosted with Docker
• Self Hosted with Kubernetes
• SaaS at flagsmith.com
• Some other way (add details in description below)

Describe the bug

See reproduction steps.

Steps To Reproduce

curl --request POST \
  --url https://edge.api.flagsmith.com/api/v1/identities/ \
  --header 'X-Environment-Key: eSxMFuFLTYjRz6enMdLSBY' \
  --header 'content-type: application/json' \
  --data '{
  "identifier": "user-123",
  "traits": [
    {
      "trait_key": "foo",
      "trait_value": true,
      "transient": true
    }
  ]
}
'

returns a 400 with no error message if the environment has allow_client_traits: false. Calling the Core API directly does return an error message:

❯ curl --request POST \
        --url https://api.flagsmith.com/api/v1/identities/ \
        --header 'X-Environment-Key: eSxMFuFLTYjRz6enMdLSBY' \
        --header 'content-type: application/json' \
        --data '{
    "identifier": "user-123",
    "traits": [
      {
        "trait_key": "foo",
        "trait_value": true,
        "transient": true
      }
    ]
  }
  '
{"traits":["Setting traits not allowed with client key."]}

Expected behavior

Return the same error messages for Core and Edge API requests; do not return 4xx error responses with no error messages.

Screenshots

No response