fix nontype errs

app.py

@@ -18,13 +18,9 @@ model = GPT2LMHeadModel.from_pretrained('checkpoint-10000')
 generation_config = GenerationConfig.from_pretrained('gpt2-medium')
 generation_config.max_new_tokens = response_length
 generation_config.pad_token_id = generation_config.eos_token_id
-
-
-
-
 def generate_response(outputs, new_prompt):
 
-    story_so_far = "\n".join(outputs[:int(1024 / response_length + 1)])
+    story_so_far = "\n".join(outputs[:int(1024 / response_length + 1)]) if outputs else ""
 
     set_seed(random.randint(0, 4000000000))
     inputs = tokenizer.encode(story_so_far + '\n' + new_prompt if story_so_far else new_prompt,
@@ -42,10 +38,10 @@ def generate_response(outputs, new_prompt):
 
 def undo(outputs):
 
-    outputs = outputs[:-1]
+    outputs = outputs[:-1] if outputs else None
     return {
         user_outputs: outputs,
-        story: "\n".join(outputs)
+        story: "\n".join(outputs) if outputs else None
     }
 
 def clean_paragraph(entry):