Fixed config_dir mode, refs #1432

datasette/app.py

@@ -278,7 +278,7 @@ class Datasette:
         if config_dir and (config_dir / "config.json").exists():
             raise StartupError("config.json should be renamed to settings.json")
         if config_dir and (config_dir / "settings.json").exists() and not settings:
-            config = json.loads((config_dir / "settings.json").read_text())
+            settings = json.loads((config_dir / "settings.json").read_text())
         self._settings = dict(DEFAULT_SETTINGS, **(settings or {}))
         self.renderers = {}  # File extension -> (renderer, can_render) functions
         self.version_note = version_note