diff --git a/companion.py b/companion.py
index f5641f01..44115248 100644
--- a/companion.py
+++ b/companion.py
@@ -182,7 +182,7 @@ def listify(thing: list | dict | None) -> list[Any]:
     JSON objects indexed by integers. Sparse arrays are converted to
     lists with gaps filled with None.
     """
-    if thing is None:
+    if not thing:
         return []
 
     if isinstance(thing, list):
@@ -1295,13 +1295,10 @@ def index_possibly_sparse_list(data: Mapping[str, V] | list[V], key: int) -> V:
     >>> index_possibly_sparse_list(data, 0)
     'test_list'
     """
-    if isinstance(data, list):
-        return data[key]
-
-    if isinstance(data, dict):
-        return data[str(key)]
-
-    raise ValueError(f'Unexpected data type {type(data)}')
+    try:
+        return data[key] if isinstance(data, list) else data[str(key)]
+    except (KeyError, IndexError) as e:
+        raise ValueError(f'Unexpected data type or missing key: {type(data)}') from e
 ######################################################################
 
 
diff --git a/prefs.py b/prefs.py
index 84f87569..7a3694b0 100644
--- a/prefs.py
+++ b/prefs.py
@@ -8,7 +8,6 @@ from pathlib import Path
 import subprocess
 import sys
 import tkinter as tk
-from os import system
 from tkinter import colorchooser as tkColorChooser  # type: ignore # noqa: N812
 from tkinter import ttk
 from itertools import count
@@ -40,12 +39,14 @@ logger = get_main_logger()
 
 def open_folder(file: Path) -> None:
     """Open the given file in the OS file explorer."""
+    # Ensure we are working with a resolved Path object
+    file_path = Path(file).resolve()
     if sys.platform.startswith('win'):
         # On Windows, use the "start" command to open the folder
-        system(f'start "" "{file}"')
+        subprocess.run(['start', '', file_path], shell=True)
     elif sys.platform.startswith('linux'):
         # On Linux, use the "xdg-open" command to open the folder
-        system(f'xdg-open "{file}"')
+        subprocess.run(['xdg-open', str(file_path)])
 
 
 def help_open_system_profiler(parent) -> None:
diff --git a/timeout_session.py b/timeout_session.py
index 03d7de85..85514bbd 100644
--- a/timeout_session.py
+++ b/timeout_session.py
@@ -40,7 +40,11 @@ class TimeoutAdapter(HTTPAdapter):
 
 
 def new_session(timeout: int = REQUEST_TIMEOUT, session: Session | None = None) -> Session:
-    """DEPRECATED: Create a new requests.Session."""
+    """
+    Create a new requests.Session.
+
+    DEPRECATED. Will be removed in a future version (6.3 or later).
+    """
     warnings.warn(
         "timeout_session.new_session() is deprecated and will be removed. "
         "Use requests.Session() directly and pass explicit timeouts to request methods.",