fix(Proxy): don't crash for responses with no body.

lib/wayfarer/server/proxy.ex

@@ -244,10 +244,20 @@ defmodule Wayfarer.Server.Proxy do
     end
   end
 
-  defp handle_responses(conn, [{:done, req} | _], mint, req) do
-    {:ok, Conn.halt(conn), mint}
+  # If the connection is done without sending any body content, then we need to
+  # send the respond and halt the conn.
+  defp handle_responses(conn, [{:done, req} | _], mint, req) when conn.state == :unset do
+    conn =
+      conn
+      |> Conn.send_resp(conn.status, "")
+      |> Conn.halt()
+
+    {:ok, conn, mint}
   end
 
+  defp handle_responses(conn, [{:done, req} | _], mint, req) when conn.state == :chunked,
+    do: {:ok, Conn.halt(conn), mint}
+
   defp handle_responses(conn, [{:error, req, reason} | _], _mint, req), do: {:error, conn, reason}
 
   defp send_request(conn, mint) do

test/wayfarer/server/proxy_test.exs

@@ -55,7 +55,7 @@ defmodule Wayfarer.Server.ProxyTest do
       {:ok, mint, req}
     end)
     |> stub(:stream, fn mint, :ignore -> {:ok, mint, responses} end)
-    |> stub(:stream, fn mint, _ -> {:ok, mint, [{:done, req}]} end)
+    |> stub(:stream, fn mint, _ -> {:ok, mint, [{:status, req, 200}, {:done, req}]} end)
   end
 
   describe "request/2" do
@@ -79,7 +79,7 @@ defmodule Wayfarer.Server.ProxyTest do
         {:ok, mint, req}
       end)
       |> expect(:stream, fn mint, :ignore ->
-        {:ok, mint, [{:done, req}]}
+        {:ok, mint, [{:status, req, 200}, {:done, req}]}
       end)
 
       assert conn = Proxy.request(conn, target)