fix: image model ranking crashes when system is not a dict (#1900)

services/hwfit/image_models.py

@@ -280,6 +280,8 @@ def rank_image_models(system, search=None, sort="fit"):
 
     Returns list of models with fit info (vram needed, fits, recommended quant).
     """
+    if not isinstance(system, dict):
+        system = {}
     gpu_vram = system.get("gpu_vram_gb", 0) or 0
     has_gpu = system.get("has_gpu", False)
     results = []

tests/test_image_models_nondict_system.py

@@ -0,0 +1,9 @@
+from services.hwfit.image_models import rank_image_models, IMAGE_MODEL_REGISTRY
+
+
+def test_rank_image_models_handles_non_dict_system():
+    # `system` is the detected-hardware dict; if detection failed and returned
+    # None (or a non-dict), system.get(...) raised AttributeError. Treat a
+    # non-dict system as "unknown hardware" (no GPU) rather than crashing.
+    assert len(rank_image_models(None)) == len(IMAGE_MODEL_REGISTRY)
+    assert len(rank_image_models(123)) == len(IMAGE_MODEL_REGISTRY)