diff --git a/git/index/base.py b/git/index/base.py
@@ -940,7 +940,7 @@ def _items_to_rela_paths(
        for item in items:
            if isinstance(item, (BaseIndexEntry, (Blob, Submodule))):
                paths.append(self._to_relative_path(item.path))
-            elif isinstance(item, str):
                paths.append(self._to_relative_path(item))
            else:
                raise TypeError("Invalid item type: %r" % item)

diff --git a/test/test_index.py b/test/test_index.py
@@ -558,14 +558,16 @@ def test_index_mutation(self, rw_repo):
        def mixed_iterator():
            count = 0
            for entry in index.entries.values():
-                type_id = count % 4
-                if type_id == 0:  # path
                    yield entry.path
-                elif type_id == 1:  # blob
                    yield Blob(rw_repo, entry.binsha, entry.mode, entry.path)
-                elif type_id == 2:  # BaseIndexEntry
                    yield BaseIndexEntry(entry[:4])
-                elif type_id == 3:  # IndexEntry
                    yield entry
                else:
                    raise AssertionError("Invalid Type")