Keep group chat session cache loading (#1418)

tests/test_group_chat_storage.py

@@ -0,0 +1,13 @@
+from pathlib import Path
+
+
+SOURCE = (
+    Path(__file__).resolve().parent.parent / "static" / "js" / "group.js"
+).read_text(encoding="utf-8")
+
+
+def test_group_session_sidebar_cache_uses_safe_json_loader():
+    assert "import Storage from './storage.js';" in SOURCE
+    assert "Storage.getJSON('odysseus-group-sessions', [])" in SOURCE
+    assert "Array.isArray(storedGroupSessions)" in SOURCE
+    assert "JSON.parse(localStorage.getItem('odysseus-group-sessions')" not in SOURCE