fix a bug with error message

modules/paths.py

@@ -12,7 +12,7 @@ for possible_sd_path in possible_sd_paths:
     if os.path.exists(os.path.join(possible_sd_path, 'ldm/models/diffusion/ddpm.py')):
         sd_path = os.path.abspath(possible_sd_path)
 
-assert sd_path is not None, "Couldn't find Stable Diffusion in any of: " + possible_sd_paths
+assert sd_path is not None, "Couldn't find Stable Diffusion in any of: " + str(possible_sd_paths)
 
 path_dirs = [
     (sd_path, 'ldm', 'Stable Diffusion'),