Ya hay una llamada a '<var>X</var>' pendiente para esta instancia de WebSocket. Se puede llamar a ReceiveAsync y a SendAsync simultáneamente, pero solo se permite una operación pendiente para cada uno de ellos al mismo tiempo.

There is already one outstanding '<var>X</var>' call for this WebSocket instance. ReceiveAsync and SendAsync can be called simultaneously, but at most one outstanding operation for each of them is allowed at the same time.

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