better redirect logic

lib/something_erlang_web/controllers/page_controller.ex

@@ -8,14 +8,23 @@ defmodule SomethingErlangWeb.PageController do
   def to_forum_path(conn, %{"to" => redir_params} = _params) do
     %{"forum_path" => path} = redir_params
 
-    with [_, thread] <- Regex.run(~r{threadid=(\d+)}, path),
-         [_, page] <- Regex.run(~r{pagenumber=(\d+)}, path) do
+    {redirect_good, thread, page} =
+      case {
+        Regex.run(~r{threadid=(\d+)}, path),
+        Regex.run(~r{pagenumber=(\d+)}, path)
+      } do
+        {[_, thread], nil} -> {:ok, thread, 1}
+        {[_, thread], [_, page]} -> {:ok, thread, page}
+        _ -> {:error, nil, nil}
+      end
+
+    if redirect_good == :ok do
       redirect(conn,
         to: Routes.thread_show_path(conn, :show, thread, page: page)
       )
+    else
+      put_flash(conn, :error, "Could not resolve URL")
+      render(conn, "index.html")
     end
-
-    put_flash(conn, :error, "Could not resolve URL")
-    render(conn, "index.html")
   end
 end