Ignore invalid imported region codes in suggestions

lib/plausible/stats/filter_suggestions.ex

@@ -47,11 +47,14 @@ defmodule Plausible.Stats.FilterSuggestions do
     |> Enum.map(fn c ->
       subdiv = Location.get_subdivision(c)
 
-      %{
-        value: c,
-        label: subdiv.name
-      }
+      if subdiv do
+        %{
+          value: c,
+          label: subdiv.name
+        }
+      end
     end)
+    |> Enum.filter(& &1)
   end
 
   def filter_suggestions(site, query, "region", filter_search) do

test/plausible_web/controllers/api/stats_controller/suggestions_test.exs

@@ -749,6 +749,39 @@ defmodule PlausibleWeb.Api.StatsController.SuggestionsTest do
       end
     end
 
+    test "ignores invalid region codes in imported data (GA4)", %{
+      conn: conn,
+      site: site,
+      site_import: site_import
+    } do
+      # NOTE: Currently, the regions imported from GA4 do not conform to region code standard
+      # we are using. Instead, literal region names are persisted. Those names often do not
+      # match the names from our region databases either. Such entries are excluded from search
+      # suggestions entirely to avoid confusion, when, for instance, a region with matching name
+      # is picked but either native or imported data is missing in the dashboard with a given
+      # filter applied when it's expected.
+      populate_stats(site, site_import.id, [
+        build(:imported_locations, country: "EE", region: "EE-37", pageviews: 2),
+        build(:imported_locations, country: "EE", region: "Hiiumaa", pageviews: 1)
+      ])
+
+      conn =
+        get(
+          conn,
+          "/api/stats/#{site.domain}/suggestions/region?q=&with_imported=true"
+        )
+
+      assert json_response(conn, 200) == [%{"value" => "EE-37", "label" => "Harjumaa"}]
+
+      conn2 =
+        get(
+          conn,
+          "/api/stats/#{site.domain}/suggestions/region?q=H&with_imported=true"
+        )
+
+      assert json_response(conn2, 200) == [%{"value" => "EE-37", "label" => "Harjumaa"}]
+    end
+
     test "ignores imported data in region suggestions when a different property is filtered by",
          %{
            conn: conn,