Replace void with expect().toBeDefined() for getter side-effect access (S3735)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

tests/stores/allMapData.test.js

@@ -236,8 +236,8 @@ describe("allMapDataStore", () => {
       store.allFilterAttrs = [
         { type: "date", min: originalDate, max: "2023-12-31T23:59:00Z" },
       ];
-      // Access the getter once
-      void store.filterAttrs;
+      // Access the getter once to trigger any side effects
+      expect(store.filterAttrs).toBeDefined();
       // The original state should still contain the ISO date, not a formatted string
       expect(store.allFilterAttrs[0].min).toBe(originalDate);
     });

tests/stores/conformance.test.js

@@ -204,7 +204,7 @@ describe("conformanceStore", () => {
           attributes: [],
         },
       ];
-      void store.cases;
+      expect(store.cases).toBeDefined();
       // Original state should still contain the ISO date
       expect(store.allCases[0].started_at).toBe(originalDate);
     });