fix(plugins): Setting a plugin setting to None removes that setting

flaschengeist/plugins/__init__.py

@@ -96,6 +96,9 @@ class Plugin:
             .one_or_none()
         )
         if setting is not None:
+            if value is None:
+                db.session.delete(setting)
+            else:
                 setting.value = value
         else:
             db.session.add(_PluginSetting(plugin=self.name, name=name, value=value))