fix dialyzer

apps/explorer/lib/explorer/chain/cache/address_sum.ex

@@ -18,7 +18,11 @@ defmodule Explorer.Chain.Cache.AddressSum do
   defp handle_fallback(:sum) do
     result = fetch_from_db()
 
-    {:update, result}
+    if Application.get_env(:explorer, __MODULE__)[:enabled] do
+      {:update, result}
+    else
+      {:return, result}
+    end
   end
 
   defp fetch_from_db do

apps/explorer/test/explorer/chain/cache/address_sum_test.exs

@@ -12,7 +12,7 @@ defmodule Explorer.Chain.Cache.AddressSumTest do
   test "returns default address sum" do
     result = AddressSum.get_sum()
 
-    assert is_nil(result)
+    assert result == 0
   end
 
   test "updates cache if initial value is zero" do