Harden settings read sanitization for invalid providers

backend/app/services/app_settings.py

@@ -587,7 +587,7 @@ def _normalize_handwriting_style_settings(payload: dict[str, Any], defaults: dic
 
 
 def _sanitize_settings(payload: dict[str, Any]) -> dict[str, Any]:
-    """Sanitizes all persisted settings into a stable normalized structure."""
+    """Sanitizes persisted settings into a stable structure while tolerating corrupt provider rows."""
 
     if not isinstance(payload, dict):
         payload = {}
@@ -603,7 +603,14 @@ def _sanitize_settings(payload: dict[str, Any]) -> dict[str, Any]:
             if not isinstance(provider_payload, dict):
                 continue
             fallback = defaults["providers"][0]
-            candidate = _normalize_provider(provider_payload, fallback_id=f"provider-{index + 1}", fallback_values=fallback)
+            try:
+                candidate = _normalize_provider(
+                    provider_payload,
+                    fallback_id=f"provider-{index + 1}",
+                    fallback_values=fallback,
+                )
+            except AppSettingsValidationError:
+                continue
             if candidate["id"] in seen_provider_ids:
                 continue
             seen_provider_ids.add(candidate["id"])