cleanup

app.py

@@ -1,6 +1,7 @@
+import os
+import shutil
 import pandas as pd
 import streamlit as st
-import os, shutil
 from tiger import tiger_exhibit, load_transcripts, TARGET_LEN, NUCLEOTIDE_TOKENS
 
 
@@ -82,5 +83,5 @@ if src_seq and all([True if nt.upper() in NUCLEOTIDE_TOKENS.keys() else False fo
         st.write('We did not find any off-target effects!')
 
 # invalid input
-else:
+elif src_seq is not None:
     st.write('Invalid input!')