Improve readability based on pr comments

Author: louiscb

lib/remote_persistent_term.ex

@@ -281,9 +281,15 @@ defmodule RemotePersistentTerm do
       start_meta,
       fn ->
         {status, version} =
-          with {:ok, current_version, updated_fetcher_state} <- state.fetcher_mod.current_version(state.fetcher_state),
+          with {:ok, current_version, updated_fetcher_state} <-
+                 state.fetcher_mod.current_version(state.fetcher_state),
                true <- state.current_version != current_version,
-               :ok <- download_and_store_term(%{state | fetcher_state: updated_fetcher_state}, deserialize_fun, put_fun) do
+               :ok <-
+                 download_and_store_term(
+                   %{state | fetcher_state: updated_fetcher_state},
+                   deserialize_fun,
+                   put_fun
+                 ) do
             {:updated, current_version}
           else
             false ->
@@ -330,28 +336,32 @@ defmodule RemotePersistentTerm do
       {:ok, deserialized} ->
         put_fun.(deserialized)
 
-      {:error, _reason} = error when state.version_fallback? ->
+      {:error, _reason} when state.version_fallback? ->
         Logger.error(
           "#{state.name} - failed to deserialize remote term, falling back to previous version"
         )
 
-        case state.fetcher_mod.previous_version(state.fetcher_state) do
-          {:ok, previous_state} ->
-            download_and_store_term(
-              %{state | fetcher_state: previous_state},
-              deserialize_fun,
-              put_fun
-            )
-
-          {:error, _} ->
-            error
-        end
+        try_previous_version(state, deserialize_fun, put_fun)
 
       error ->
         error
     end
   end
 
+  defp try_previous_version(state, deserialize_fun, put_fun) do
+    case state.fetcher_mod.previous_version(state.fetcher_state) do
+      {:ok, previous_state} ->
+        download_and_store_term(
+          %{state | fetcher_state: previous_state},
+          deserialize_fun,
+          put_fun
+        )
+
+      {:error, _} = error ->
+        error
+    end
+  end
+
   defp maybe_decompress(%__MODULE__{auto_decompress?: true}, body) do
     case body do
       <<0x1F, 0x8B, _rest::binary>> = gzipped ->

lib/remote_persistent_term/fetcher/http.ex

@@ -82,7 +82,7 @@ defmodule RemotePersistentTerm.Fetcher.Http do
   end
 
   @impl true
-  def previous_version(_state), do: {:error, :no_previous_version}
+  def previous_version(_state), do: {:error, :not_supported}
 
   defp response_status(url, status) do
     if status < 300 do

lib/remote_persistent_term/fetcher/static.ex

@@ -28,7 +28,7 @@ defmodule RemotePersistentTerm.Fetcher.Static do
       def download(state), do: {:ok, unquote(Macro.escape(Keyword.fetch!(opts, :data)))}
 
       @impl true
-      def previous_version(_), do: {:error, :no_previous_version}
+      def previous_version(_), do: {:error, :not_supported}
     end
   end
 end