Added `auth_template/0` to DatabaseAuthenticator.

lib/pleroma/web/auth/database_authenticator.ex

@@ -17,4 +17,9 @@ def get_user(plug), do: implementation().get_user(plug)
 
   @callback handle_error(Plug.Conn.t(), any()) :: any()
   def handle_error(plug, error), do: implementation().handle_error(plug, error)
+
+  @callback auth_template() :: String.t() | nil
+  def auth_template do
+    implementation().auth_template() || Pleroma.Config.get(:auth_template, "show.html")
+  end
 end

lib/pleroma/web/auth/pleroma_database_authenticator.ex

@@ -23,4 +23,6 @@ def get_user(%Plug.Conn{} = conn) do
   def handle_error(%Plug.Conn{} = _conn, error) do
     error
   end
+
+  def auth_template, do: nil
 end

lib/pleroma/web/oauth/oauth_controller.ex

@@ -25,9 +25,7 @@ def authorize(conn, params) do
     available_scopes = (app && app.scopes) || []
     scopes = oauth_scopes(params, nil) || available_scopes
 
-    template = Pleroma.Config.get(:auth_template, "show.html")
-
-    render(conn, template, %{
+    render(conn, DatabaseAuthenticator.auth_template(), %{
       response_type: params["response_type"],
       client_id: params["client_id"],
       available_scopes: available_scopes,