{:amqp_msg, {:P_basic, ...:undefined, :undefined, :undefined, :undefined} AMQP error :( - rabbitmq

Question

Error I am getting
{:amqp_msg, {:P_basic, :undefined, :undefined, :undefined, 1, :undefined,
:undefined, :undefined, :undefined, :undefined, :undefined, :undefined,
:undefined, :undefined, :undefined}
Error type :exit
This happens under the load testing, when I am trying to publish a message into the queue.
I am using ExRabbitPool which has AMQP as it's underlying call out.
If I have 30 requests per seconds, all fine, when start going over it then I start getting errors.
I am using seperate pool for Producer and Consumer and there are enough channels for them. Here are some code
def queue_config, do: [
queue_name: "some_queue_name",
exchange: "some_exchange_name",
queue_options: [durable: true],
exchange_options: [type: :topic],
bind_options: [routing_key: "some_routing_name"]
]
ExRabbitPool.with_channel(pool_id, fn {:ok, channel} ->
try do
with :ok <- ExRabbitPool.RabbitMQ.declare_exchange(channel, exchange, exchange_options),
:ok <- ExRabbitPool.RabbitMQ.publish(channel, exchange, routing_key, Jason.encode!(message), options) do
Logger.info "Published message to the queue #{queue_name}"
{:ok, message}
else
{:error, reason} -> Logger.error("Error publishing message to queue #{pool_id} #{queue_name} #{inspect reason}")
{:error, reason}
end
catch type, error ->
msg = %{message: "Fatal error occurred when publishing to the queue #{pool_id} #{queue_name} #{inspect type} #{inspect error}", error: error}
Logger.error(Exception.format(type, msg, __STACKTRACE__))
{:error, msg}
end
end)
Sample Error:
06:23:51.304 pid=<0.24534.2> ... [error] ** (exit) %{error: {:normal, {:gen_server, :call, [#PID<0.25408.2>, {:call, {:"basic.publish", 0, "result_exchange", "", false, false}, {:amqp_msg, {:P_basic, :undefined, :undefined, :undefined, 1, :undefined, :undefined, :undefined, :undefined, :undefined, :undefined, :undefined, :undefined, :undefined, :undefined}, "[{\"retry_no\":0,\"service_type\":\"someservice\",\"some_id\":123}]"}, #PID<0.24534.2>}, 60000]}}, message: "Fatal error occurred when publishing to the queue producer_pool some_queue :exit {:normal, {:gen_server, :call, [#PID<0.25408.2>, {:call, {:\"basic.publish\", 0, \"result_exchange\", \"\", false, false}, {:amqp_msg, {:P_basic, :undefined, :undefined, :undefined, 1, :undefined, :undefined, :undefined, :undefined, :undefined, :undefined, :undefined, :undefined, :undefined, :undefined}, \"[{\\\"retry_no\\\":0,\\\"service_type\\\":\\\"someservice\\\",\\\"some_id\\\":123}]\"}, #PID<0.24534.2>}, 60000]}}"}
So under the load I get the Fatal error...
Code is pretty simple, I think it might be something at the RabbitMQ config? not sure.
What do you think?