Add Discogs function to fetch artist image

lib/discogs/api.ex

@@ -12,6 +12,17 @@ defmodule Discogs.API do
     |> get_request()
   end
 
+  def get_artist_image(url, config) do
+    case Req.new(url: url, max_retries: 1, user_agent: config.user_agent)
+         |> Req.Request.merge_options(config.req_options)
+         |> Req.Request.append_request_steps(log_attempt: &log_attempt/1)
+         |> Req.Request.append_response_steps(log_error: &log_error/1)
+         |> get_request() do
+      {:ok, data} -> {:ok, data}
+      {:error, _reason} -> {:error, :cover_not_available}
+    end
+  end
+
   defp new_request(config) do
     Req.new(
       base_url: "https://api.discogs.com",
@@ -42,4 +53,15 @@ defmodule Discogs.API do
     Logger.debug("Fetching data from #{url}")
     request
   end
+
+  defp log_error({request, response}) do
+    if response.status in 400..499 or response.status in 500..599 do
+      Logger.error(fn ->
+        url = URI.to_string(request.url)
+        "Failed to fetch data from #{url}, reason: #{inspect(response.body)}"
+      end)
+    end
+
+    {request, response}
+  end
 end