remove error message for unauthenticated users and trigger rerun on successful login

app.py

@@ -117,7 +117,6 @@ def update_vote(
 
 
 if 'loggedin' not in st.session_state: # user is not logged in
-    st.error("You are not logged in")
     with st.form("login"):
         username = st.selectbox("Select voter", voters)
         password = st.text_input("Password (get password from contact@osbm.dev)", type="password")
@@ -131,6 +130,7 @@ if 'loggedin' not in st.session_state: # user is not logged in
             st.success("Welcome, " + username)
             st.write("You are now logged in")
             st.session_state['loggedin'] = username
+            st.rerun()
 
 else: # logged in
     username = st.session_state['loggedin']