[Bug]: [spec-1.0] Sending an invalid message to the server raises an InternalServerError

[jmesnil]

What happened?

More info at https://github.com/a2aproject/a2a-tck/pull/98/files#r2592807248

but TL;DR if my branch of TCK send a 'SendMessage' to the server with an invalid payload (missing required role and parts fields:

{"message": {"messageId": "123"}}

it raises the error {'code': -32603, 'message': "Parameter 'role' may not be null"} that corresponds to an InternalError.
When I look at the logs of my server, the IllegalArgumentException from the Message.Builder is not catched and raised as a valid spec error (should be InvalidRequestError imho)

Relevant log output

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[ehsavoie]

Should it be an InvalidRequestError or InvalidParamsError ?

[jmesnil]

We should follow the guidance at https://a2a-protocol.org/latest/specification/#332-error-handling

Validation Errors: Invalid input parameters or message format
Servers MUST validate all input parameters before processing
[...]
Example error codes: HTTP 400 Bad Request, gRPC INVALID_ARGUMENT, JSON-RPC -32602 Invalid params
Example scenarios: Invalid task ID format, missing required message parts, unsupported content type

Any serialisation issues such at #512 fits that category, so it should be InvalidParamsError (contrary to what I wrote in the issue description)

[ehsavoie]

Ok, makes sense :)
thanks