Update app.py

app.py

@@ -46,10 +46,10 @@ with gr.Blocks() as demo:
     embed_key(os.environ.get("OPENAI_API_KEY"), study_tutor)
     # The instructor will also provide a secret prompt to initialize the chat bot
     text_input = gr.TextArea(label='Copy and paste your text below', value=os.environ.get("SECRET_PROMPT"), lines=2)
-    file_input = None
-    instructor_input = None
+    file_input = ""
+    instructor_input = ""
     api_input = os.environ.get("OPENAI_API_KEY")
-    learning_objectives = None
+    learning_objectives = ""
     
     with gr.Row():
       vs_build_button = gr.Button(value = 'Start Studying with Your Tutor!', scale=1)