SSE: Getting "closed" instead of :closed when client disconnects

[fladens]

Hello everyone 👋 Thanks for this great package!

I am using

• absinthe_plug (1.5.8)
• Phoenix (1.7.14)
• Bandit (1.5.5).

I use Server-Sent-Events for graphql subscriptions and I am running into the following issue when the client disconnects, for example through closing of a tab or reloading.

[error] ** (CaseClauseError) no case clause matching: {:error, "closed"}
    (absinthe_plug 1.5.8) lib/absinthe/plug.ex:385: Absinthe.Plug.subscribe_loop/3

for the lines here:

absinthe_plug/lib/absinthe/plug.ex

Lines 373 to 397 in 3a984cc

	receive do
	%{event: "subscription:data", payload: %{result: result}} ->
	case chunk(conn, "#{encode_json!(result, config)}\n\n") do
	{:ok, conn} ->
	subscribe_loop(conn, topic, config)
	{:error, :closed} ->
	Absinthe.Subscription.unsubscribe(config.context.pubsub, topic)
	conn
	end
	:close ->
	Absinthe.Subscription.unsubscribe(config.context.pubsub, topic)
	conn
	after
	30_000 ->
	case chunk(conn, ":ping\n\n") do
	{:ok, conn} ->
	subscribe_loop(conn, topic, config)
	{:error, :closed} ->
	Absinthe.Subscription.unsubscribe(config.context.pubsub, topic)
	conn
	end
	end

It seems to me I would just need to add {:error, "closed"}, however, since it feels a bit redundant and I am quite new to elixir wanted to make sure this is what is indeed needed.

I can create a PR for it though.

---

It might be a difference in how Bandit and Cowboy are handling errors, not sure if I can possibly overwrite this to actually return atoms instead, couldn't find anything though.