improving app default values

app.py

@@ -97,10 +97,13 @@ def main():
         on_change=company_type_changed,
     )
 
+    if 'offer' not in st.session_state:
+        st.session_state['offer'] = choice(EXAMPLE_OFFERS.get(email_company_type))
+
     email_offer = st.sidebar.text_area(
         label="Offer description",
         key="offer",
-        value=choice(EXAMPLE_OFFERS.get("bank")),
+        value=st.session_state['offer'],
         height=200,
     )
 
@@ -122,7 +125,7 @@ def main():
     )
 
     with st.form(key="form"):
-        if st.form_submit_button(label='Generate email', disabled=len(prompt_input) == 0):
+        if st.form_submit_button(label='Generate email', disabled=prompt_input is None or len(prompt_input) == 0):
             with st.spinner("Generating email..."):
                 output = generate_email(prompt_input, max_tokens=max_tokens_input)
             st.markdown("----")