Fix: Use default model name if env var is empty

utils.py

@@ -15,8 +15,8 @@ models_config = {
     "Apriel-1.5-15B-thinker": {
         "MODEL_DISPLAY_NAME": "Apriel-1.5-15B-thinker",
         "MODEL_HF_URL": "https://huggingface.co/ServiceNow-AI/Apriel-1.5-15b-Thinker",
-        "MODEL_NAME": os.environ.get("MODEL_NAME_APRIEL_1_5_15B", "Apriel-1.5-15B-thinker"),
-        "VLLM_API_URL": os.environ.get("VLLM_API_URL_APRIEL_1_5_15B", "http://localhost:8080/v1"),
+        "MODEL_NAME": os.environ.get("MODEL_NAME_APRIEL_1_5_15B") or "Apriel-1.5-15B-thinker",
+        "VLLM_API_URL": os.environ.get("VLLM_API_URL_APRIEL_1_5_15B") or "http://localhost:8080/v1",
         "VLLM_API_URL_LIST": os.environ.get("VLLM_API_URL_LIST_APRIEL_1_5_15B"),
         "REASONING": True,
         "MULTIMODAL": True,