Fixed typo

app.py

@@ -247,7 +247,7 @@ def generate(
         raise gr.Error("""
             The number of boxes should be equal to the number of subjects.
             Number of boxes drawn: {}, number of subjects: {}.
-        """.format(len(boxes), nun_subjects))
+        """.format(len(boxes), num_subjects))
 
     filter_token_indices = convert_token_indices(filter_token_indices) if len(filter_token_indices.strip()) > 0 else None
     num_tokens = int(num_tokens) if len(num_tokens.strip()) > 0 else None