Gin Transport panics and crashes entire process when the users requests unsupported method

[teodormarianmck]

Steps to reproduce:

• Start as gin server
• run:

curl --location 'http://localhost:8000/mcp' \
--header 'Content-Type: application/json' \
--data '{
    "jsonrpc": "2.0",
    "id": 1,
    "method": "tools/list_invalid",
    "params": {
        "submitter": "test",
        "content": {
        }
    }
}

• unrecoverable panic (on different go routine) "invalid memory address or nil pointer dereference" because JsonRpcResponse is undefined

if err := p.transport.Send(ctx, transport.NewBaseMessageError(response)); err != nil {
	p.handleError(fmt.Errorf("failed to send error response: %w", err))
}
...
// Send implements Transport.Send
func (t *GinTransport) Send(ctx context.Context, message *transport.BaseJsonRpcMessage) error {
	key := message.JsonRpcResponse.Id
	responseChannel := t.responseMap[int64(key)]
	if responseChannel == nil {
		return fmt.Errorf("no response channel found for key: %d", key)
	}
	responseChannel <- message
	return nil
}

• this in turn crashes the entire process using the MCP lib

[1garo]

I would like to start contributing, it's okay if I try this one?

[ecekyn]

hey @1garo ! yep definitely. feel free to pick up any issue :)