fix(lora): handle missing files for already loaded networks

Add check to mark networks as unavailable when they are already loaded
in memory but their source files no longer exist on disk. This prevents
errors when attempting to use networks whose files have been deleted
after initial loading.

The change adds an additional condition in load_networks() to verify
file existence for previously loaded networks and properly adds them
to the unavailable_networks list for cleanup.

Author: bluelovers

extensions-builtin/Lora/networks.py

@@ -305,6 +305,9 @@ def load_networks(names, te_multipliers=None, unet_multipliers=None, dyn_dims=No
         net = get_network_on_disk(name)
         if net is None:
             unavailable_networks.append(name)
+        elif already_loaded.get(name, None) is not None and not os.path.exists(net.filename):
+            # already loaded but file doesn't exist
+            unavailable_networks.append(name)
 
     if unavailable_networks:
         update_available_networks_by_names(unavailable_networks)