Update event producer from gen stage queue broadcaster

lib/hook/event_producer.ex

@@ -11,21 +11,27 @@ defmodule Accent.Hook.EventProducer do
         {:producer, {:queue.new(), 0}, dispatcher: GenStage.BroadcastDispatcher}
       end
 
-      def handle_call({_, event}, from, {queue, demand}) do
-        dispatch_events(:queue.in({from, event}, queue), demand, [])
+      def handle_call({_, event}, from, {queue, pending_demand}) do
+        queue = :queue.in({from, event}, queue)
+        dispatch_events(queue, pending_demand, [])
       end
 
-      def handle_demand(incoming_demand, {queue, demand}) do
-        dispatch_events(queue, incoming_demand + demand, [])
+      def handle_demand(incoming_demand, {queue, pending_demand}) do
+        dispatch_events(queue, incoming_demand + pending_demand, [])
+      end
+
+      defp dispatch_events(queue, 0, events) do
+        {:noreply, Enum.reverse(events), {queue, 0}}
       end
 
       defp dispatch_events(queue, demand, events) do
-        with d when d > 0 <- demand,
-             {{:value, {from, event}}, queue} <- :queue.out(queue) do
-          GenStage.reply(from, :ok)
-          dispatch_events(queue, demand - 1, [event | events])
-        else
-          _ -> {:noreply, Enum.reverse(events), {queue, demand}}
+        case :queue.out(queue) do
+          {{:value, {from, event}}, queue} ->
+            GenStage.reply(from, :ok)
+            dispatch_events(queue, demand - 1, [event | events])
+
+          {:empty, queue} ->
+            {:noreply, Enum.reverse(events), {queue, demand}}
         end
       end
     end