fix: wrong return value caused metric sending to fail sometimes (#3638)

Author: icehaunter

.changeset/brown-ducks-admire.md

@@ -0,0 +1,5 @@
+---
+'@core/sync-service': patch
+---
+
+fix: wrong return value caused metric sending to fail sometimes

packages/sync-service/lib/electric/shapes/consumer_registry.ex

@@ -44,7 +44,10 @@ defmodule Electric.Shapes.ConsumerRegistry do
 
   @spec active_consumer_count(stack_id()) :: non_neg_integer()
   def active_consumer_count(stack_id) when is_binary(stack_id) do
-    :ets.info(ets_name(stack_id), :size)
+    case :ets.info(ets_name(stack_id), :size) do
+      :undefined -> 0
+      size -> size
+    end
   rescue
     ArgumentError -> 0
   end