Handle short input

app.py

@@ -63,7 +63,8 @@ inputs = tokenizer([text])
 [input_ids] = inputs["input_ids"]
 window_len = min(window_len, len(input_ids))
 
-if len(input_ids) < 1:
+if len(input_ids) < 2:
+    st.error("Please enter at least 2 tokens.", icon="🚨")
     st.stop()
 
 @st.cache_data(show_spinner=False)