[BACKEND] More explicit error message for PermissionError (#736)

Do not print the full stack trace when a PermissionError occurs

src/ytdl_sub/utils/logger.py

@@ -221,6 +221,13 @@ class Logger:
             # Log validation exceptions as-is
             if isinstance(exception, ValidationException):
                 logger.error(str(exception))
+            # Log permission errors explicitly
+            elif isinstance(exception, PermissionError):
+                logger.error(
+                    "A permission error occurred:\n%s\n"
+                    "The user running ytdl-sub must have permission to this file/directory.",
+                    str(exception),
+                )
             # For other uncaught errors, log as bug:
             else:
                 logger.exception("An uncaught error occurred:")

tests/unit/main/test_main.py

@@ -69,6 +69,21 @@ def test_main_uncaught_error(capsys, mock_sys_exit, expected_uncaught_error_mess
     assert mock_error.call_args.args[2] == Logger.debug_log_filename()
 
 
+def test_main_permission_error(capsys, mock_sys_exit, expected_uncaught_error_message):
+    permission_error = PermissionError("test")
+    with mock_sys_exit(expected_exit_code=1), patch(
+        "src.ytdl_sub.main._main", side_effect=permission_error
+    ), patch.object(logging.Logger, "error") as mock_error:
+        main()
+
+    assert mock_error.call_count == 1
+    assert mock_error.call_args.args[0] == (
+        "A permission error occurred:\n%s\n"
+        "The user running ytdl-sub must have permission to this file/directory."
+    )
+    assert mock_error.call_args.args[1] == "test"
+
+
 def test_args_after_sub_work(mock_sys_exit):
     with mock_sys_exit(expected_exit_code=0), patch.object(
         sys,