MODEL_AUTHENTICATION
Your model provider is denying you access to their service.
Troubleshooting
The following may help resolve this error:
- Confirm that your API key or other credentials are correct.
 - If you are relying on an environment variable to authenticate, confirm that the variable name is correct and that it has a value set.
- Note that some environments, like Cloudflare Workers, do not support environment variables.
 - For some models, you can try explicitly passing an 
apiKeyparameter to rule out any environment variable issues like this: 
 
const model = new ChatOpenAI({
  model: "MODEL_NAME",
  apiKey: "YOUR_KEY_HERE",
});
- If you are using a proxy or other custom endpoint, make sure that your custom provider does not expect an alternative authentication scheme.