Fix config corruption

The previous commit may set your sg1,sg2,audio_sg to QVariant([]) rather
than "[]".

vocabsieve/config/base_tab.py

@@ -1,8 +1,4 @@
-from PyQt5.QtWidgets import (QDialog, QStatusBar, QCheckBox, QComboBox, QLineEdit,
-                             QSpinBox, QPushButton, QSlider, QLabel, QHBoxLayout,
-                             QWidget, QTabWidget, QMessageBox, QColorDialog, QListWidget,
-                             QFormLayout, QGridLayout, QVBoxLayout
-                             )
+from PyQt5.QtWidgets import (QCheckBox, QComboBox, QLineEdit, QSpinBox, QSlider, QWidget, QListWidget)
 from PyQt5.QtCore import QTimer
 from enum import Enum
 import json
@@ -56,10 +52,6 @@ def update_map(v):
         def update_json(v):
             settings.setValue(key, json.dumps(v))
 
-        # Initialize the setting if not present
-        if settings.value(key) is None:
-            settings.setValue(key, default)
-
         if isinstance(widget, QCheckBox):
             widget.setChecked(settings.value(key, default, type=bool))
             widget.clicked.connect(update)