Fix MacOS web execution flow (#1899)

* fix metal device path for chatbot

* single device remove indexing

* lint fix

apps/stable_diffusion/web/ui/stablelm_ui.py

@@ -153,6 +153,7 @@ def chat(
 
     device_id = None
     model_name, model_path = list(map(str.strip, model.split("=>")))
+    device = device if "=>" not in device else device.split("=>")[1].strip()
     if "cuda" in device:
         device = "cuda"
     elif "sync" in device:
@@ -164,6 +165,8 @@ def chat(
         device = "vulkan"
     elif "rocm" in device:
         device = "rocm"
+    elif "metal" in device:
+        device = "metal"
     else:
         print("unrecognized device")
 
@@ -331,6 +334,8 @@ def llm_chat_api(InputData: dict):
         elif "vulkan" in device:
             device_id = int(device.split("://")[1])
             device = "vulkan"
+        elif "metal" in device:
+            device = "metal"
         else:
             print("unrecognized device")